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Sample records for erosive wear characteristics

  1. Erosive tooth wear in children

    NARCIS (Netherlands)

    Carvalho, T.S.; Lussi, A.; Jaeggi, T.; Gambon, D.L.; Lussi, A.; Ganss, C.

    2014-01-01

    Erosive tooth wear in children is a common condition. Besides the anatomical differences between deciduous and permanent teeth, additional histological differences may influence their susceptibility to dissolution. Considering laboratory studies alone, it is not clear whether deciduous teeth are

  2. Elevated temperature erosive wear of metallic materials

    International Nuclear Information System (INIS)

    Roy, Manish

    2006-01-01

    Solid particle erosion of metals and alloys at elevated temperature is governed by the nature of the interaction between erosion and oxidation, which, in turn, is determined by the thickness, pliability, morphology, adhesion characteristics and toughness of the oxide scale. The main objective of this paper is to critically review the present state of understanding of the elevated temperature erosion behaviour of metals and alloys. First of all, the erosion testing at elevated temperature is reviewed. This is followed by discussion of the essential features of elevated temperature erosion with special emphasis on microscopic observation, giving details of the erosion-oxidation (E-O) interaction mechanisms. The E-O interaction has been elaborated in the subsequent section. The E-O interaction includes E-O maps, analysis of transition criteria from one erosion mechanism to another mechanism and quantification of enhanced oxidation kinetics during erosion. Finally, the relevant areas for future studies are indicated. (topical review)

  3. Erosive and Mechanical Tooth Wear in Viking Age Icelanders.

    Science.gov (United States)

    Richter, Svend; Eliasson, Sigfus Thor

    2017-08-29

    (1) Background: The importance of the Icelandic Sagas as a source of information about diet habits in medieval Iceland, and possibly other Nordic countries, is obvious. Extensive tooth wear in archaeological material worldwide has revealed that the main cause of this wear is believed to have been a coarse diet. Near the volcano Hekla, 66 skeletons dated from before 1104 were excavated, and 49 skulls could be evaluated for tooth wear. The purpose of this study was to determine the main causes of tooth wear in light of diet and beverage consumption described in the Sagas; (2) Materials and methods: Two methods were used to evaluate tooth wear and seven for age estimation; (3) Results: Extensive tooth wear was seen in all of the groups, increasing with age. The first molars had the highest score, with no difference between sexes. These had all the similarities seen in wear from a coarse diet, but also presented with characteristics that are seen in erosion in modern Icelanders, through consuming excessive amounts of soft drinks. According to the Sagas, acidic whey was a daily drink and was used for the preservation of food in Iceland, until fairly recently; (4) Conclusions: It is postulated that the consumption of acidic drinks and food, in addition to a coarse and rough diet, played a significant role in the dental wear seen in ancient Icelanders.

  4. Control of erosive tooth wear: possibilities and rationale

    Directory of Open Access Journals (Sweden)

    Mônica Campos Serra

    2009-06-01

    Full Text Available Dental erosion is a type of wear caused by non bacterial acids or chelation. There is evidence of a significant increase in the prevalence of dental wear in the deciduous and permanent teeth as a consequence of the frequent intake of acidic foods and drinks, or due to gastric acid which may reach the oral cavity following reflux or vomiting episodes. The presence of acids is a prerequisite for dental erosion, but the erosive wear is complex and depends on the interaction of biological, chemical and behavioral factors. Even though erosion may be defined or described as an isolated process, in clinical situations other wear phenomena are expected to occur concomitantly, such as abrasive wear (which occurs, e.g, due to tooth brushing or mastication. In order to control dental loss due to erosive wear it is crucial to take into account its multifactorial nature, which predisposes some individuals to the condition.

  5. Standard Terminology Relating to Wear and Erosion

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 The terms and their definitions given herein represent terminology relating to wear and erosion of solid bodies due to mechanical interactions such as occur with cavitation, impingement by liquid jets or drops or by solid particles, or relative motion against contacting solid surfaces or fluids. This scope interfaces with but generally excludes those processes where material loss is wholly or principally due to chemical action and other related technical fields as, for instance, lubrication. 1.2 This terminology is not exhaustive; the absence of any particular term from this collection does not necessarily imply that its use within this scope is discouraged. However, the terms given herein are the recommended terms for the concepts they represent unless otherwise noted. 1.3 Certain general terms and definitions may be restricted and interpreted, if necessary, to make them particularly applicable to the scope as defined herein. 1.4 The purpose of this terminology is to encourage uniformity and accuracy ...

  6. Study of corrosive-erosive wear behaviour of Al6061/albite composites

    International Nuclear Information System (INIS)

    Sharma, S.C.; Krishna, M.; Murthy, H.N. Narasimha; Tarachandra, R.; Satyamoorthy, M.; Bhattacharyya, D.

    2006-01-01

    This investigation analyses the influence of dispersed alumina particles on the wear behaviour of the Al/albite composites in a corrosive environment. The composites were prepared by modified pressure die-casting technique. The corrosive-erosive wear experiments were carried out on a proprietary corrosion-erosion wear tester to study the wear characteristics of the composites. The slurry was made up of water and alumina (size: 90-150 μm, proportion: 0-30 wt.%), while H 2 SO 4 (0.01, 0.1 and 1N) was added to create the corrosive conditions. Experiments were arranged to test the relationships among the corrosive-erosive wear rate, concentrations of H 2 SO 4 and alumina in the slurry, weight percent of albite in the composite, erosion speed and distance. Wear rate varies marginally at low speeds but sharply increases at higher speeds. The corrosive wear rate logarithmically increased with the increasing concentration of the corrosive medium. The effect of abrasive particles and corrosion medium on the wear behaviour of the composite is explained experimentally, theoretically and using scanning electron microscopy

  7. Testing of a Fiber Optic Wear, Erosion and Regression Sensor

    Science.gov (United States)

    Korman, Valentin; Polzin, Kurt A.

    2011-01-01

    The nature of the physical processes and harsh environments associated with erosion and wear in propulsion environments makes their measurement and real-time rate quantification difficult. A fiber optic sensor capable of determining the wear (regression, erosion, ablation) associated with these environments has been developed and tested in a number of different applications to validate the technique. The sensor consists of two fiber optics that have differing attenuation coefficients and transmit light to detectors. The ratio of the two measured intensities can be correlated to the lengths of the fiber optic lines, and if the fibers and the host parent material in which they are embedded wear at the same rate the remaining length of fiber provides a real-time measure of the wear process. Testing in several disparate situations has been performed, with the data exhibiting excellent qualitative agreement with the theoretical description of the process and when a separate calibrated regression measurement is available good quantitative agreement is obtained as well. The light collected by the fibers can also be used to optically obtain the spectra and measure the internal temperature of the wear layer.

  8. Reduction of Erosion Wear of Mean Pressure Cylinder of Steam Turbines Operating Beyond Critical Parameters

    Directory of Open Access Journals (Sweden)

    V. P. Kascheev

    2009-01-01

    Full Text Available The paper considers problems leading to erosion wear of flowing part of a mean pressure turbine cylinder operating beyond critical parameters. Explanation of erosion wear of flowing part of a mean pressure turbine cylinder which is proved in practice and recommendations for wear reduction are given in the paper

  9. Erosive Wear of Inconel 625 Alloy Coatings Deposited by CMT Method

    Directory of Open Access Journals (Sweden)

    Solecka M.

    2016-06-01

    Full Text Available The article presents the investigation results concerning the determination of the characteristics of erosive wear caused by the impact of Al2O3 solid particles on the surface of Inconel 625 alloy after plastic working and the same material after weld cladding process using the CMT method. Erosion wear tests were performed at two temperatures: 20°C and 650°C. The erosion tests were conducted using the standard ASTM G76. A jet with a specified abrasive waight was directed to the surface of the tested material at an α impingement angle varied in the range of 30-90° at a velocity imparted to the abrasive by the medium, which was compressed air. The eroded surface was examined using a scanning electron microscope (SEM, while the depths of craters caused by the erosion tests were measured with an optical profilometer. The predominant mechanisms of the formation of mass losses during solid particle erosion were microcutting and microfissuring.

  10. Erosive Wear Characterization of Materials for Lunar Construction

    Science.gov (United States)

    Mpagazehe, Jeremiah N.; Street, Kenneth W., Jr.; Delgado, Irebert R.; Higgs, C. Fred, III

    2012-01-01

    NASA s Apollo missions revealed that exhaust from the retrorockets of landing spacecraft may act to significantly accelerate lunar dust on the surface of the Moon. A recent study by Immer et al. (C. Immer, P.T. Metzger, P.E. Hintze, A. Nick, and R. Horan, Apollo 12 Lunar Module exhaust plume impingement on Lunar Surveyor III, Icarus, Vol. 211, pp. 1089-1102, 2011) investigated coupons returned to Earth from the Surveyor III lunar probe which were subjected to lunar dust impingement by the Apollo 12 Lunar Module landing. Their study revealed that even with indirect impingement, the spacecraft sustained erosive damage from the fast-moving lunar dust particles. In this work, results are presented from a series of erosive wear experiments performed on 6061 Aluminum using the JSC-1AF lunar dust simulant. Optical profilometry was used to investigate the surface after the erosion process. It was found that even short durations of lunar dust simulant impacting at low velocities produced substantial changes in the surface.

  11. Bedrock erosion by sliding wear in channelized granular flow

    Science.gov (United States)

    Hung, C. Y.; Stark, C. P.; Capart, H.; Smith, B.; Maia, H. T.; Li, L.; Reitz, M. D.

    2014-12-01

    Boundary forces generated by debris flows can be powerful enough to erode bedrock and cause considerable damage to infrastructure during runout. Bedrock wear can be separated into impact and sliding wear processes. Here we focus on sliding wear. We have conducted experiments with a 40-cm-diameter grainflow-generating rotating drum designed to simulate dry channelized debris flows. To generate sliding erosion, we placed a 20-cm-diameter bedrock plate axially on the back wall of the drum. The rotating drum was half filled with 2.3-mm-diameter grains, which formed a thin grain-avalanching layer with peak flow speed and depth close to the drum axis. The whole experimental apparatus was placed on a 100g-ton geotechnical centrifuge and, in order to scale up the stress level, spun to a range of effective gravity levels. Rates and patterns of erosion of the bedrock plate were mapped after each experiment using 3d micro-photogrammetry. High-speed video and particle tracking were employed to measure granular flow dynamics. The resulting data for granular velocities and flow geometry were used to estimate impulse exchanges and forces on the bedrock plate. To address some of the complexities of granular flow under variable gravity levels, we developed a continuum model framed around a GDR MiDi rheology. This model allowed us to scale up boundary forcing while maintaining the same granular flow regime, and helped us to understand important aspects of the flow dynamics including e.g. fluxes of momentum and kinetic energy. In order to understand the detailed processes of boundary forcing, we performed numerical simulations with a new contact dynamics model. This model confirmed key aspects of our continuum model and provided information on second-order behavior such as fluctuations in the forces acting on the wall. By combining these measurements and theoretical analyses, we have developed and calibrated a constitutive model for sliding wear that is a threshold function of

  12. A new in situ model to study erosive enamel wear, a clinical pilot study.

    NARCIS (Netherlands)

    Ruben, J.L.; Truin, G.J.; Bronkhorst, E.M.; Huysmans, M.C.D.N.J.M.

    2017-01-01

    OBJECTIVES: To develop an in situ model for erosive wear research which allows for more clinically relevant exposure parameters than other in situ models and to show tooth site-specific erosive wear effect of an acid challenge of orange juice on enamel. METHODS: This pilot study included 6

  13. Influence of Intrinsic Factors on Erosive Tooth Wear in a Large-Scale Epidemiological Study.

    Science.gov (United States)

    Alaraudanjoki, Viivi; Laitala, Marja-Liisa; Tjäderhane, Leo; Pesonen, Paula; Lussi, Adrian; Ronkainen, Jukka; Anttonen, Vuokko

    2016-01-01

    To assess the influence of self-reported intrinsic factors [gastroesophageal reflux disease (GERD), long-term alcoholism, long-term heavy use of alcohol and multiple pregnancies] on erosive tooth wear in a middle-aged cohort sample. Of the total Northern Finland Birth Cohort (NFBC 1966), a convenience sample (n = 3,181) was invited for an oral health examination in 2012-2013, of which 1,962 participated, comprising the final study group. Erosive tooth wear was assessed by sextants using the Basic Erosive Wear Examination Index (BEWE, 0-18). Clinical data were supplemented by questionnaires conducted in 1997/1998 and 2012/2013. The participants were divided into severe (BEWE sum ≥9) and no-to-moderate (BEWE sum 0-8) erosive wear groups, and the logistic regression model was applied. Selected intrinsic factors were quite rare in this cohort sample and explained only 5.9% of the difference in the prevalence and severity of erosive wear. Daily symptoms of GERD [odds ratio (OR) 3.8, confidence interval (CI) 1.2-12.0] and hyposalivation (OR 3.8, CI 1.2-11.8) were the strongest risk indicators for severe erosive wear. Additionally, variables associated with an elevated risk for severe erosive wear were diagnosed alcoholism at any point (OR 2.5, CI 0.7-9.7) and self-reported heavy use of alcohol in both questionnaires (OR 2.0, CI 0.6-6.2). Even low-dose long-term consumption of alcohol was associated with erosive wear. In this cohort sample, intrinsic factors such as GERD or alcoholism alone are relatively uncommon causes of erosive tooth wear. The role of long-term use of alcohol in the erosion process may be bigger than presumed. © 2016 S. Karger AG, Basel.

  14. Effect of ion implantation on subsequent erosion and wear behavior of solids

    International Nuclear Information System (INIS)

    McHargue, C.J.

    1985-01-01

    The removal of material from a solid surface by mechanical forces is influenced by material properties (hardness, fracture toughness, yield strength, surface free energy) as well as system parameters (force, velocity of loading, environment). Ion implantation can modify many of the material properties either by directly affecting the deformation characteristics or indirectly by affecting the chemical or phase composition at the surface. The various forms of wear and erosion are analyzed to determine the material and system parameters which control material removal. The effects of implantation on these critical parameters are noted and examples of changes in surface topography under various test conditions are discussed. 18 figs

  15. Investigation on wear characteristic of biopolymer gear

    Science.gov (United States)

    Ghazali, Wafiuddin Bin Md; Daing Idris, Daing Mohamad Nafiz Bin; Sofian, Azizul Helmi Bin; Basrawi, Mohamad Firdaus bin; Khalil Ibrahim, Thamir

    2017-10-01

    Polymer is widely used in many mechanical components such as gear. With the world going to a more green and sustainable environment, polymers which are bio based are being recognized as a replacement for conventional polymers based on fossil fuel. The use of biopolymer in mechanical components especially gear have not been fully explored yet. This research focuses on biopolymer for spur gear and whether the conventional method to investigate wear characteristic is applicable. The spur gears are produced by injection moulding and tested on several speeds using a custom test equipment. The wear formation such as tooth fracture, tooth deformation, debris and weight loss was observed on the biopolymer spur gear. It was noted that the biopolymer gear wear mechanism was similar with other type of polymer spur gears. It also undergoes stages of wear which are; running in, linear and rapid. It can be said that the wear mechanism of biopolymer spur gear is comparable to fossil fuel based polymer spur gear, thus it can be considered to replace polymer gears in suitable applications.

  16. Erosion wear response of epoxy composites filled with steel industry slag and sludge particles: A comparative study

    Science.gov (United States)

    Purohit, Abhilash; Satapathy, Alok

    2018-03-01

    In the field of composite research, use of industrial wastes such as slag and sludge particles as filler in wear resistant polymer composites has not been very common. Owing to the very high cost of conventional filler materials in polymer composites, exploring the possibility of using low cost minerals and industrial wastes for this purpose has become the need of the hour. In this context this work explores the possibility of such polymer composites filled with low cost industrial wastes and presents a comparison of mechanical characteristics among three types of epoxy based composites filled with Linz - Donawitz sludge (LD sludge), blast furnace slag (BF slag) and Linz - Donawitz slag (LD slag) respectively. A comparative study in regard to their solid particle erosion wear characteristics under similar test conditions is also included. Composites with different weight proportions (0, 5, 10, 15 and 20 wt. %) of LD sludge are fabricated by solution casting technique. Mechanical properties such as micro- hardness, tensile strength and flexural strength of three types of composites have been evaluated as per ASTM test standards and solid particle erosion wear test is performed following a design of experiment approach based on Taguchi’s orthogonal array. Five control factors (impact velocity, erodent size, filler content, impingement angle and erodent temperature) each at five levels are considered to conduct erosion wear tests. The test results for epoxy-LD sludge composites are compared with those of epoxy-BF slag and epoxy-LD slag composites reported by previous investigators. The comparison reveals that epoxy filled with LD sludge exhibits superior mechanical and erosion wear characteristics among the three types of composites considered in this study. This work also opens up a new avenue for value added utilization of an abundant industrial waste in the making of epoxy based functional composites.

  17. Reduction of Erosive Wear in situ by Stannous Fluoride-Containing Toothpaste.

    NARCIS (Netherlands)

    Huysmans, M.C.D.N.J.M.; Jager, D.H.; Ruben, J.L.; Unk, D.E.; Klijn, C.P.; Vieira, A.M.

    2011-01-01

    Background/Aims: Stannous fluoride (SnF) has been suggested as a dental erosion-preventive agent. The aim of this single-centre, randomized, double-blind, in situ study was to evaluate the effect of toothpastes with SnF in the prevention of erosive enamel wear. Methods: A combined split-mouth

  18. Dental approach to erosive tooth wear in gastroesophageal reflux ...

    African Journals Online (AJOL)

    2014-06-02

    Jun 2, 2014 ... Objective: To summarize the diagnostic protocol and treatment of dental erosion due to GERD. Methods: A Medline ..... reflux in children with cerebral palsy and its relationship to erosion of ... phate (ACP) on root surface hypersensitivity. Operative ... Lussi A. Dental erosion clinical diagnosis and case.

  19. Variations in erosive wear of metallic materials with temperature via the electron work function

    International Nuclear Information System (INIS)

    Huang, Xiaochen; Yu, Bin; Yan, X.G.; Li, D.Y.

    2016-01-01

    Mechanical properties of metals are intrinsically determined by their electron behavior, which is largely reflected by the electron work function (EWF or φ). Since the work function varies with temperature, the dependence of material properties on temperature could be predicted via variations in work function with temperature. Combining a hardness – φ relationship and the dependence of work function on temperature, a temperature-dependent model for predicting solid-particle erosion is proposed. Erosive wear losses of copper, nickel, and carbon steel as sample materials were measured at different temperatures. Results of the tests are consistent with the theoretical prediction. This study demonstrates a promising parameter, electron work function, for looking into fundamental aspects of wear phenomena, which would also help develop alternative methodologies for material design. - Highlights: • Metallic materials' wear resistance is influenced by temperature. • Electron work function (EWF) intrinsically determines materials' wear resistance. • An EWF-based temperature-dependent solid-particle erosion model is proposed.

  20. Dental approach to erosive tooth wear in gastroesophageal reflux ...

    African Journals Online (AJOL)

    Background: The duration of gastro-esophageal reflux disease (GERD), the frequency of reflux, the pH and type of acid, and the quality and quantity of saliva affect the severity of dental erosion due to GERD. Objective: To summarize the diagnostic protocol and treatment of dental erosion due to GERD. Methods: A Medline ...

  1. HIGH TEMPERATURE EROSION WEAR OF CERMET PARTICLES REINFORCED SELF-FLUXING ALLOY MATRIX HVOF SPRAYED COATINGS

    Directory of Open Access Journals (Sweden)

    Andrei Surzhenkov

    2015-09-01

    Full Text Available In the present paper, the resistance of high velocity oxy-fuel (HVOF sprayed TiC-NiMo and Cr3C2-Ni cermet particles reinforced NiCrSiB self-fluxing alloy matrix coatings to high temperature erosion wear is studied. Microstructure of the coatings was examined by SEM, phase composition was determined by XRD. A four-channel centrifugal particle accelerator was applied to study the high temperature erosion wear of the coatings. The impact angles were 30 and 90 degrees, initial particle velocity was 50 m/s, temperature of the test - 650 degrees. Volume wear of the coatings was calculated and compared to the respective values of the reference materials. Wear mechanisms were studied by SEM.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7617

  2. Erosive wear of a surface coated hydroturbine steel

    Indian Academy of Sciences (India)

    Administrator

    Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee,. Roorkee ... turbines, pipelines and valves used in slurry transporta- tion of matter ... city gas blast erosion rig facility developed as per standard.

  3. Erosion wear of boron carbide ceramic nozzles by abrasive air-jets

    International Nuclear Information System (INIS)

    Deng Jianxin

    2005-01-01

    Boron carbide nozzles were produced by hot pressing. The erosion wear of this nozzle caused by abrasive particle impact was investigated by abrasive air-jets. Silica, silicon carbide and alumina powders with different hardness were used as the erodent abrasive particles. Results showed that the hardness of the erodent particles played an important role with respect to the erosion wear of the boron carbide nozzles. As the hardness of the erodent particles increases, there is a dramatic increase in erosion rate of the nozzles. The nozzle entrance area suffered from severe abrasive impact under large impact angles, and generated maximum tensile stresses. The wear mechanisms of boron carbide nozzle at this area appeared to be entirely brittle in nature with the evidence of large scale-chipping, and exhibited a brittle fracture induced removal process. While at the nozzle center wall section, most of the particles traveled parallel to the nozzle wall, and showed minimum tensile stresses. The wear mode in this area of the nozzle changed from impact to sliding erosion, and the wear mechanisms appeared to be the lateral cracking owing to a surface fatigue fracture mechanism

  4. Use of dentifrices to prevent erosive tooth wear: harmful or helpful?

    Directory of Open Access Journals (Sweden)

    Ana Carolina Magalhães

    2014-01-01

    Full Text Available Dental erosion is the loss of dental hard tissues caused by non-bacterial acids. Due to acid contact, the tooth surface becomes softened and more prone to abrasion from toothbrushing. Dentifrices containing different active agents may be helpful in allowing rehardening or in increasing surface resistance to further acidic or mechanical impacts. However, dentifrices are applied together with brushing and, depending on how and when toothbrushing is performed, as well as the type of dentifrice and toothbrush used, may increase wear. This review focuses on the potential harmful and helpful effects associated with the use of dentifrices with regard to erosive wear. While active ingredients like fluorides or agents with special anti-erosive properties were shown to offer some degree of protection against erosion and combined erosion/abrasion, the abrasive effects of dentifrices may increase the surface loss of eroded teeth. However, most evidence to date comes from in vitro and in situ studies, so clinical trials are necessary for a better understanding of the complex interaction of active ingredients and abrasives and their effects on erosive tooth wear.

  5. Simultaneous acid exposure and erosive particle wear of thermoset coatings

    DEFF Research Database (Denmark)

    Møller, Victor Buhl; Dam-Johansen, Kim; Frankær, Sarah Maria

    2018-01-01

    , similar to the erosion/corrosion-type phenomena found in metals. A vinyl ester-based coating was the most resistant to the simultaneous erosive/acidic exposure, with a maximum polishing rate of 3.24±0.61 μm/week, while novolac epoxy and polyurethane coatings showed high polishing rates of 11.7±1.50 and 13.4±0......Handling acidic chemicals is a challenge in the chemical industry, requiring a careful choice of contact material. Certain thermoset organic coatings are applicable in low pH environments, but when particulate erosion is also present the performance demand is increased. This is the case in, e...

  6. Predicting local distributions of erosion-corrosion wear sites for the piping in the nuclear power plant using CFD models

    International Nuclear Information System (INIS)

    Ferng, Y.M.

    2008-01-01

    The erosion-corrosion (E/C) wear is an essential degradation mechanism for the piping in the nuclear power plant, which results in the oxide mass loss from the inside of piping, the wall thinning, and even the pipe break. The pipe break induced by the E/C wear may cause costly plant repairs and personal injures. The measurement of pipe wall thickness is a useful tool for the power plant to prevent this incident. In this paper, CFD models are proposed to predict the local distributions of E/C wear sites, which include both the two-phase hydrodynamic model and the E/C models. The impacts of centrifugal and gravitational forces on the liquid droplet behaviors within the piping can be reasonably captured by the two-phase model. Coupled with these calculated flow characteristics, the E/C models can predicted the wear site distributions that show satisfactory agreement with the plant measurements. Therefore, the models proposed herein can assist in the pipe wall monitoring program for the nuclear power plant by way of concentrating the measuring point on the possible sites of severe E/C wear for the piping and reducing the measurement labor works

  7. Variations in erosive wear of metallic materials with temperature via the electron work function

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiaochen; Yu, Bin [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4 (Canada); Yan, X.G. [School of Mechanical Engineering, Taiyuan University of Science and Technology, Taiyuan, Shanxi (China); Li, D.Y., E-mail: dongyang.li@ualberta.ca [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4 (Canada); School of Mechanical Engineering, Taiyuan University of Science and Technology, Taiyuan, Shanxi (China)

    2016-04-01

    Mechanical properties of metals are intrinsically determined by their electron behavior, which is largely reflected by the electron work function (EWF or φ). Since the work function varies with temperature, the dependence of material properties on temperature could be predicted via variations in work function with temperature. Combining a hardness – φ relationship and the dependence of work function on temperature, a temperature-dependent model for predicting solid-particle erosion is proposed. Erosive wear losses of copper, nickel, and carbon steel as sample materials were measured at different temperatures. Results of the tests are consistent with the theoretical prediction. This study demonstrates a promising parameter, electron work function, for looking into fundamental aspects of wear phenomena, which would also help develop alternative methodologies for material design. - Highlights: • Metallic materials' wear resistance is influenced by temperature. • Electron work function (EWF) intrinsically determines materials' wear resistance. • An EWF-based temperature-dependent solid-particle erosion model is proposed.

  8. Erosion by sliding wear in granular flows: Experiments with realistic contact forces

    Science.gov (United States)

    Stark, C. P.; Hung, C. Y.; Smith, B.; Li, L.; Grinspun, E.; Capart, H.

    2015-12-01

    Debris flow erosion is a powerful and sometimes dominant process in steep channels. Despite its importance, this phenomenon is relatively little studied in the lab. The large drum experiments of Hsu are a notable exception, in which almost-field-scale impact forces were generated at the head of a synthetic debris flow whose properties (grain size, proportion of fines, etc) were varied widely.A key challenge in these and similar experiments is to explore how erosion rate varies as a function of the scale of the flow (thereby varying inertial stresses, impact forces, etc). The geometrical limitations of most lab experiments, and their short run time, severely limit the scope of such explorations.We achieve this scale exploration in a set of drum erosion experiments by varying effective gravity across several orders of magnitude (1g, 10g, 100g) in a geotechnical centrifuge. By half-filling our 40cm-diameter drum with dry 2.3mm grains, placing a synthetic rock plate at the back and a glass plate at the front 3cm apart, and rotating the drum at 1-50rpm, we simulate wear in a channelized dry granular flow. In contrast to Hsu's experiments, we focus on sliding wear erosion at the flow boundary rather than impact/frictional wear at the flow head. By varying effective gravity from 1g-100g we can tune the pressure exerted by the grains at the boundary without having to change the scale of our apparatus. Using a recently developed depth-averaged, kinetic-energy closure theory for granular flow, we can simultaneously tune the drum rotation rate such that the flow dynamics remain invariant. We can thereby explore how changing the scale of a granular flow, and thus the contact forces of grains on the boundary, controls the rate of rock erosion. Using a small apparatus we can simulate the erosion generated by debris flows several meters deep involving grains up to 10cm in diameter.Our results suggest that sliding wear is the main erosion process, and are consistent with Archard

  9. Vibrational characteristics and wear of fuel rods

    International Nuclear Information System (INIS)

    Schmugar, K.L.

    1977-01-01

    Fuel rod wear, due to vibration, is a continuing concern in the design of liquid-cooled reactors. In my report, the methodology and models that are used to predict fuel rod vibrational response and vibratory wear, in a light water reactor environment, are discussed. This methodology is being followed at present in the design of Westinghouse Nuclear Fuel. Fuel rod vibrations are expressed as the normal bending modes, and sources of rod vibration are examined with special emphasis on flow-induced mechanisms in the stable flow region. In a typical Westinghouse PWR fuel assembly design, each fuel rod is supported at multiple locations along the rod axis by a square-shaped 'grid cell'. For a fuel rod /grid support system, the development of small oscillatory motions, due to fluid flow at the rod/grid interface, results in material wear. A theoretical wear mode is developed using the Archard Theory of Adhesive Wear as the basis. Without question certainty, fretting wear becomes a serious problem if it progresses to the stage where the fuel cladding is penetrated and fuel is exposed to the coolant. Westinghouse fuel is designed to minimize fretting wear by limiting the relative motion between the fuel rod and its supports. The wear producing motion between the fuel rod and its supports occurs when the vibration amplitude exceeds the slippage threshold amplitude

  10. On researching erosion-corrosion wear in pipelines: the rate and residual lifetime estimation

    International Nuclear Information System (INIS)

    Baranenko, V.I.; Yanchenko, Yu.A.; Gulina, O.M.; Dokukin, D.A.

    2010-01-01

    To base the normative document on calculation of pipelines erosive-corrosive wear (ECW) rate and residual lifetime this research of ECW regularities for pearlitic steel NPP pipelines was performed. The estimates of control data treatment statistical procedures efficiency were presented. The influence of the scheme of piping control on the ECW rate and residual lifetime estimation results was demonstrated. The simplified scheme is valid only in case of complete information. It's usage under data uncertainties leads to essential residual lifetime overstating [ru

  11. Study of the Parametric Performance of Solid Particle Erosion Wear under the Slurry Pot Test Rig

    Directory of Open Access Journals (Sweden)

    S.R. More

    2017-12-01

    Full Text Available Stainless Steel (SS 304 is commonly used material for slurry handling applications like pipelines, valves, pumps and other equipment's. Slurry erosion wear is a common problem in many engineering applications like process industry, thermal and hydraulic power plants and slurry handling equipments. In this paper, experimental investigation of the influence of solid particle size, impact velocity, impact angle and solid concentration parameters in slurry erosion wear behavior of SS 304 using slurry pot test rig. In this study the design of experiments was considered using Taguchi technique. A comparison has been made for the experimental and Taguchi technique results. The erosion wear morphology was studied using micro-graph obtained by scanning electron microscope (SEM analysis. At shallow impact angle 30°, the material removal pattern was observed in the form of micro displacing, scratching and ploughing with plastic deformation of the material. At 60° impact angle, mixed type of micro indentations and pitting action is observed. At normal impact angle 90°, the material removal pattern was observed in form of indentation and rounded lips. It is found that particle velocity was the most influence factor than impact angle, size and solid concentration. From this investigation, it can be concluded that the slurry erosion wear is minimized by controlling the slurry flow velocity which improves the service life of the slurry handling equipments. From the comparison of experimental and Taguchi experimental design results it is found that the percentage deviation was very small with a higher correlation coefficient (r2 0.987 which is agreeable.

  12. Wear Characteristics of Metallic Biomaterials: A Review

    Science.gov (United States)

    Hussein, Mohamed A.; Mohammed, Abdul Samad; Al-Aqeeli, Naser

    2015-01-01

    Metals are extensively used in a variety of applications in the medical field for internal support and biological tissue replacements, such as joint replacements, dental roots, orthopedic fixation, and stents. The metals and alloys that are primarily used in biomedical applications are stainless steels, Co alloys, and Ti alloys. The service period of a metallic biomaterial is determined by its abrasion and wear resistance. A reduction in the wear resistance of the implant results in the release of incompatible metal ions into the body that loosen the implant. In addition, several reactions may occur because of the deposition of wear debris in tissue. Therefore, developing biomaterials with high wear resistance is critical to ensuring a long life for the biomaterial. The aim of this work is to review the current state of knowledge of the wear of metallic biomaterials and how wear is affected by the material properties and conditions in terms of the type of alloys developed and fabrication processes. We also present a brief evaluation of various experimental test techniques and wear characterization techniques that are used to determine the tribological performance of metallic biomaterials.

  13. Tooth wear and erosion: methodological issues in epidemiological and public health research and the future research agenda.

    Science.gov (United States)

    Ganss, C; Young, A; Lussi, A

    2011-09-01

    This paper addresses methodological issues in the field of tooth wear and erosion research including the epidemiological indices, and identifies future work that is needed to improve knowledge about tooth wear and erosion. The paper is result of the work done at the meetings of the Special Interest Group "Tooth Surface Loss and Erosion" at the 2008, 2009 and 2010 conferences of the European Association for Dental Public Health, and the Workshop "Current Erosion indices- flawed or valid" which took place in Basel in 2007. Although there is consensus about the definition and the diagnostic criteria of various forms of tooth wear, gaps in research strategies have been identified. A basic problem is that fundamental concepts of wear and erosion as an oral health problem, have not yet been sufficiently defined. To a certain extent, tooth wear is a physiological condition, and there is no consensus as to whether it can be regarded as a disease. Furthermore, the multitude of indices and flaws in existing indices, make published data difficult to interpret. Topics for the research agenda are: the initiation of a consensus process towards an internationally accepted index, and the initiation of data collection on the prevalence of various forms of wear on a population-based level. There should be an emphasis on promoting communication between basic and clinical sciences, and the area of Public Health Dentistry. Furthermore, the question of whether tooth wear is a public health problem remains open for debate.

  14. Influence of Coating with Some Natural Based Materials on the Erosion Wear Behavior of Glass Fiber Reinforced Epoxy Resin

    OpenAIRE

    Aseel Basim Abdul Hussein; Emad Saadi AL-Hassani; Reem Alaa Mohamed

    2015-01-01

    In the present study, composites were prepared by Hand lay-up molding. The composites constituents were epoxy resin as a matrix, 6% volume fractions of glass fibers (G.F) as reinforcement and 3%, 6% volume fractions of preparation natural material (Rice Husk Ash, Carrot Powder, and Sawdust) as filler. Studied the erosion wear behavior and coating by natural wastes (Rice Husk Ash) with epoxy resin after erosion. The results showed the non – reinforced epoxy have lower resistance erosion than n...

  15. Fractal characteristic in the wearing of cutting tool

    Science.gov (United States)

    Mei, Anhua; Wang, Jinghui

    1995-11-01

    This paper studies the cutting tool wear with fractal geometry. The wearing image of the flank has been collected by machine vision which consists of CCD camera and personal computer. After being processed by means of preserving smoothing, binary making and edge extracting, the clear boundary enclosing the worn area has been obtained. The fractal dimension of the worn surface is calculated by the methods called `Slit Island' and `Profile'. The experiments and calciating give the conclusion that the worn surface is enclosed by a irregular boundary curve with some fractal dimension and characteristics of self-similarity. Furthermore, the relation between the cutting velocity and the fractal dimension of the worn region has been submitted. This paper presents a series of methods for processing and analyzing the fractal information in the blank wear, which can be applied to research the projective relation between the fractal structure and the wear state, and establish the fractal model of the cutting tool wear.

  16. The effect of daily fluoride mouth rinsing on enamel erosive/abrasive wear in situ.

    Science.gov (United States)

    Stenhagen, K R; Hove, L H; Holme, B; Tveit, A B

    2013-01-01

    It is not known whether application of fluoride agents on enamel results in lasting resistance to erosive/abrasive wear. We investigated if one daily mouth rinse with sodium fluoride (NaF), stannous fluoride (SnF(2)) or titanium tetrafluoride (TiF(4)) solutions protected enamel against erosive/abrasive wear in situ (a paired, randomised and blind study). Sixteen molars were cut into 4 specimens, each with one amalgam filling (measurement reference surface). Two teeth (2 × 4 specimens) were mounted bilaterally (buccal aspects) on acrylic mandibular appliances and worn for 9 days by 8 volunteers. Every morning, the specimens were brushed manually with water (30 s) extra-orally. Then fluoride solutions (0.4% SnF(2) pH 2.5; 0.15% TiF(4) pH 2.1; 0.2% NaF pH 6.5, all 0.05 M F) were applied (2 min). Three of the specimens from each tooth got different treatment, and the fourth served as control. At midday, the specimens were etched for 2 min in 300 ml fresh 0.01 M hydrochloric acid and rinsed in tap water. This etch procedure was repeated in the afternoon. Topographic measurements were performed by a white-light interferometer. Mean surface loss (±SD) for 16 teeth after 9 days was: SnF(2) 1.8 ± 1.9 µm, TiF(4) 3.1 ± 4.8 µm, NaF 26.3 ± 4.7 µm, control 32.3 ± 4.4 µm. Daily rinse with SnF(2), TiF(4) and NaF resulted in 94, 90 and 18% reduction in enamel erosive/abrasive wear, respectively, compared with control (p < 0.05). The superior protective effect of daily rinse with either stannous or titanium tetrafluoride solutions on erosive/abrasive enamel wear is promising. Copyright © 2012 S. Karger AG, Basel.

  17. Investigation of friction and wear characteristics of palm biodiesel

    International Nuclear Information System (INIS)

    Fazal, M.A.; Haseeb, A.S.M.A.; Masjuki, H.H.

    2013-01-01

    Highlights: ► Both wear and friction decrease with the increase of biodiesel concentration. ► Wear and friction appear to decrease more at the range of 10–20% biodiesel in diesel blend. ► The wear of steel ball in biodiesel (B100) was 20% lower than that in diesel (B0). ► Lubricity in terms of wear and friction decreases with the increase of rotating speed. - Abstract: Use of biodiesel in automobile engine is creating tribology related new challenges. The present study aims to assess the friction and wear characteristics of palm biodiesel at different concentration level by using four-ball wear machine. The investigated fuels were biodiesel (B100), diesel (B0) and three different biodiesel blends such as B10 (10% biodiesel in diesel), B20, B50. Tests were conducted at 75 °C under a normal load of 40 kg for 1 h at four different speeds viz, 600, 900, 1200 and 1500 rpm. Worn surfaces of the balls were examined by SEM. Results showed that wear and friction decreased with the increase of biodiesel concentration. The wear of steel ball in B100 was appeared to be 20% lower than that in diesel (B0)

  18. Vibration and wear characteristics of steam generator tubes

    International Nuclear Information System (INIS)

    Choi, Young Hwan

    2003-06-01

    This study investigates the fluid elastic instability characteristics of Steam Generator (SG) U-tubes with defect and the safety assessment of the potential for fretting-wear damages on Steam Generator (SG) U-tubes caused by foreign object in operating nuclear power plants. The operating SG shell-side flow field conditions for determining the fluid elastic instability or fretting-wear parameters such as damping ratio, added mass and flow velocity are obtained from three-dimensional SG flow calculation using the ATHOS3 code. To get the natural frequency, corresponding mode shape and participation factor, modal analyses are performed for the U-tubes either with axial or circumferential flaw with different sizes. Special emphases are on the effects of flaw orientation and size on the modal and instability characteristics of tubes, which are expressed in terms of the natural frequency, corresponding mode shape and stability ratio. Also, the wear rate of U-tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted, and discussed in this study is the effect of the flow velocity and vibration of the tube on the remaining life of the tube. In addition, addressed is the effect of the internal pressure on the vibration and fretting-wear characteristics of the tube

  19. Rapid Analyses of Polyetheretherketone Wear Characteristics by Accelerated Wear Testing with Microfabricated Surfaces for Artificial Joint Systems.

    Science.gov (United States)

    Su, Chen-Ying; Kuo, Chien-Wei; Fang, Hsu-Wei

    2017-01-01

    Wear particle-induced biological responses are the major factors resulting in the loosening and then failure of total joint arthroplasties. It is feasible to improve the lubrication and reduce the wear of artificial joint system. Polyetheretherketone (PEEK) is considered as a potential bearing material due to its mechanical characteristics of resistance to fatigue strain. The PEEK wear particles have been indicated to be involved in biological responses in vitro, and further studies regarding the wear phenomena and wear particle generation are needed. In this study, we have established an accelerated wear testing system with microfabricated surfaces. Various contact pressures and lubricants have been utilized in the accelerated wear tests. Our results showed that increasing contact pressure resulted in an increase of wear particle sizes and wear rate, and the size of PEEK wear particles can be controlled by the feature size of microfabricated surfaces. These results provided the information rapidly about factors that affect the morphology and amount of PEEK wear particles and can be applied in the future for application of PEEK on the biological articulation system.

  20. Registration of dental erosive wear on study models and intra-oral photographs.

    Science.gov (United States)

    Hove, L H; Mulic, A; Tveit, A B; Stenhagen, K R; Skaare, A B; Espelid, I

    2013-02-01

    Clinical photographs and study models may provide permanent records of dental erosion and be useful supplements to clinical registration. To assess the reliability and validity of registrations on clinical photographs and study models performed by a group of examiners. Thirty tooth surfaces were selected and assessed clinically, using the visual erosion dental examination system. The chosen surfaces provided the whole range of dental erosions including sound surfaces. The tooth surfaces were photographed and impressions were obtained for preparation of study models. Thirty-three dentists examined and scored the selected surfaces both on photographs and study models. The quality of diagnosis (AUC, area under curve) was slightly higher using photographs as compared to study models. The difference was statistically significant when the validation criterion was erosion, assuming dentine exposure. The inter-method agreement on photographs and study models versus the clinical evaluation were approximately in the same range with a mean κw of 0.48 and 0.43, respectively. When comparing study models with photographs the mean κw was 0.52. The intra-examiner agreement was strong/substantial for both (photographs mean κw = 0.63 and study models mean κw = 0.60). Linear weighted Cohen's kappa (κw) was used to evaluate inter-method and intra-examiner agreement. Receiver operating characteristic and area under the curves were used to express diagnostic quality according to a clinical examination. The results indicated that photographs were as good as study models for recording erosive lesions.

  1. Cannon Wear and Erosion Science and Technology Objective Program (STO) 155-mm Projectile Rotating Band/Obturation for Extended Range

    Science.gov (United States)

    2015-06-01

    refractory metal coatings such as chrome plating have slowed the erosion at the origin but have not prevented down bore wear. Down bore wear is due...in the current projectile inventory: the M107, M864/M549A1, and the M483A1 types (fig. 1). The band material is either copper or a copper/ zinc alloy... ductility and sufficient tensile (shear) strength in order to engrave and survive 300 in. of tube travel. In the materials, these properties are

  2. Study on Co-free amorphous material cladding using a laser beam to improve the resistance of primary system parts in NPPs to wear/erosion-corrosion

    International Nuclear Information System (INIS)

    Kim, J. S.; Woo, S. S.; Seo, J. H.

    2001-01-01

    A study on Co-free amorphous material, ARMACOR M, cladding using a laser beam has been performed to improve resistance of the primary system main parts on nuclear power plants to wear/erosion-corrosion. The wear/erosion-corrosion properties of ARMACRO M cladded speciemens were characterized in air at room temperature and 300 .deg. C and in air at room temperature, and compared to those of other hardfacing materials, such as Stellite 6, NOREM 02, Deloro 50, TIG-welde or laer cladded. According to the results, ARMACOR M laser-cladded specimen showed to have the highest resistance to wear/erosion-corrosion

  3. Fretting friction and wear characteristics of magnetorheological fluid under different magnetic field strengths

    International Nuclear Information System (INIS)

    Zhang, P.; Lee, K.H.; Lee, C.H.

    2017-01-01

    A magnetorheological fluid (MRF) performs differently under different magnetic field strength. This study examined the fretting friction and wear characteristics of MRFs under a range of magnetic field strengths and oscillation frequencies. The fretting friction and wear behaviors of MRF are investigated using a fretting friction and wear tester. The surfaces of specimen are examined by optical microscopy and 3D surface profilometer before and after the tests and wear surface profiles, the wear volume loss and wear coefficient for each magnetic field strength are evaluated. The results show that the friction and wear properties of MRF change according to the magnetic field strength and oscillation frequency. - Highlights: • Fretting friction and wear characteristics of MRF is examined. • The friction coefficients increased with increasing magnetic field strength. • The coefficient of friction decreased with increasing oscillation frequency. • Wear volume and coefficient become worse with increasing magnetic field strength.

  4. Comprehensive study of the abrasive wear and slurry erosion behavior of an expanded system of high chromium cast iron and microstructural modification for enhanced wear resistance

    Science.gov (United States)

    Chung, Reinaldo Javier

    High chromium cast irons (HCCIs) have been demonstrated to be an effective material for a wide range of applications in aggressive environments, where resistances to abrasion, erosion and erosion-corrosion are required. For instance, machinery and facilities used in mining and extraction in Alberta's oil sands suffer from erosion and erosion-corrosion caused by silica-containing slurries, which create challenges for the reliability and maintenance of slurry pumping systems as well as other processing and handling equipment. Considerable efforts have been made to determine and understand the relationship between microstructural features of the HCCIs and their wear performance, in order to guide the material selection and development for specific service conditions with optimal performance. The focus was previously put on a narrow group of compositions dictated by ASTM A532. However, with recent advances in casting technology, the HCCI compositional range can be significantly expanded, which potentially brings new alloys that can be superior to those which are currently employed. This work consists of three main aspects of study. The first one is the investigation of an expanded system of white irons with their composition ranging from 1 to 6 wt.% C and 5 to 45 wt.% Cr, covering 53 alloys. This work has generated wear and corrosion maps and established correlation between the performance and microstructural features for the alloys. The work was conducted in collaboration with the Materials Development Center of Weir Minerals in Australia, and the results have been collected in a database that is used by the company to guide materials selection for slurry pump components in Alberta oil sands and in other mining operations throughout the world. The second part consists of three case studies on effects of high chromium and high carbon, respectively, on the performance of the HCCIs. The third aspect is the development of an approach to enhance the wear resistance of

  5. Microstructure and erosive wear behaviors of Ti6Al4V alloy treated by plasma Ni alloying

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z.X.; Wu, H.R.; Shan, X.L.; Lin, N.M.; He, Z.Y., E-mail: tyuthzy@126.com; Liu, X.P.

    2016-12-01

    Graphical abstract: The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition were investigated by thermal field emission scanning electron microscopy (SEM), and glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD), respectively. The cross-section nano-scale hardness of Ni modified layer was measured by nano indenter. The results showed that Ni modified layers exhibited triple layers structure and continuous gradient distribution of the concentration. From the surface to the matrix, they were 2 μm Ni deposition layer, 8 μm Ni-rich alloying layer including the phases of Ni{sub 3}Ti, NiTi, Ti{sub 2}Ni, AlNi{sub 3} and 24 μm Ni-poor alloying layer forming the solid solution of nickel. With increasing of the thickness of Ni modified layer, the microhardness increased first, reached the climax, then gradient decreased. The erosion tests were performed on the surface of the untreated and treated Ti6Al4V sample using MSE (Micro-slurry-jet Erosion) method. The experiment results showed that the wear rate of every layer showed different value, and the Ni-rich alloying layer was the lowest. The strengthening mechanism of Ni modified layer was also discussed. - Highlights: • The Ni modified layers were prepared by the plasma surface alloying technique. • Triple layers structure was prepared. • Using Micro-slurry-jet Erosion method. • The erosion rate of Ni modified layer experienced the process of descending first and then ascending. • Improvement of erosion resistance performance of Ni-rich alloying layer was prominent. The wear mechanism of Ni modified layer showed micro-cutting wearing. - Abstract: The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition

  6. Characteristics of fracture during the approach process and wear mechanism of a silicon AFM tip

    International Nuclear Information System (INIS)

    Chung, Koo-Hyun; Lee, Yong-Ha; Kim, Dae-Eun

    2005-01-01

    The wear of an atomic force microscope (AFM) tip is one of the crucial issues in AFM as well as in other probe-based applications. In this work, wear tests under extremely low normal load using an AFM were conducted. Also, in order to understand the nature of silicon tip wear, the wear characteristics of crystal silicon and amorphous silicon oxide layer were investigated by a high-resolution transmission electron microscope (HRTEM). It was found that fracture of the tip readily occurred due to impact during the approach process. Experimental results showed that the impact should be below 0.1 nN s to avoid significant fracture of the tip. Also, it was observed that wear of the amorphous layer, formed at the end of the tip, occurred at the initial stage of the silicon tip damage process. Based on Archard's wear law, the wear coefficient of the amorphous layer was in the range of 0.009-0.014. As for the wear characteristics of the silicon tip, it was shown that wear occurred gradually under light normal load and the wear rate decreased with increase in the sliding distance. As for the wear mechanism of the silicon tip, oxidation wear was identified to be the most significant. It was shown that the degree of oxidation was higher under high normal load and in a nitrogen environment, oxidation of the silicon tip was reduced

  7. Protective Effect of Adhesive Systems associated with Neodymium-doped Yttrium Aluminum Garnet Laser on Enamel Erosive/Abrasive Wear.

    Science.gov (United States)

    Crastechini, Erica; Borges, Alessandra B; Becker, Klaus; Attin, Thomas; Torres, Carlos Rg

    2017-10-01

    This study evaluated the efficacy of self-etching adhesive systems associated or not associated with the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser on the protection against enamel erosive/abrasive wear. Bovine enamel specimens were demineralized with 0.3% citric acid (5 minutes). The samples were randomly assigned to eight groups (n = 20): SB - Single Bond Universal (3M/ESPE); SB+L - Single Bond Universal + laser (80 mJ/10 Hz); FB - Futurabond U (Voco); FB+L -Futurabond U + laser; GEN - G-aenial bond (GC); GEN+L -G-aenial bond + laser; L - laser irradiation; and C - no treatment. The laser was applied before light curing. The samples were subjected to erosive/abrasive challenges (0.3% citric acid - 2 minutes and tooth brushing four times daily for 5 days). Enamel surface loss was recovered profilometrically by comparison of baseline and final profiles. The adhesive layer thickness, retention percentage of the protective layer, and microhardness of cured adhesive were measured. Data were analyzed using one-way analysis of variance and Tukey's test (5%). There were significant differences for all parameters (p = 0.0001). Mean values ± SD and results of the Tukey's test were: Surface wear: GEN - 4.88 (±1.09)a, L - 5.04 ± 0.99)a, FB - 5.32 (±0.93)ab, GEN + L - 5.46 (±1.27)abc, SB + L - 5.78 (±1.12)abc, FB + L - 6.23 (±1.25)bc, SB - 6.35 (±1.11)c, and C - 6.46 (±0.61)c; layer thickness: GEN - 15.2 (±8.63)c, FB - 5.06 (±1.96)a, GEN + L - 13.96 (±7.07)bc, SB + L - 4.24 (±2.68)a, FB + L - 9.03 (±13.02)abc, and SB - 7.49 (±2.80)ab; retention: GEN - 68.89 (±20.62)c, FB - 54.53 (±24.80)abc, GEN + L - 59.90 (±19.79)abc, SB + L - 63.37 (±19.30)bc, FB + L - 42.23 (±17.68) a, and SB - 47.78 (±18.29)ab; microhardness: GEN - 9.27 (±1.75)c; FB - 6.99 (±0.89)b; GEN + L - 6.22 (±0.87)ab; SB + L - 15.48 (±2.51)d; FB + L - 10.67 (±1.58)c; SB - 5.00 (±1.60)a. The application of Futurabond U and G-aenial bond on enamel surface, as well as the Nd

  8. Investigation of friction and wear characteristics of cast iron material under various conditions

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Ji Hoon; Kim, Chang Lae; Oh, Jeong Taek; Kim, Dae Eun [Yonsei University, Seoul (Korea, Republic of); Nemati, Narguess [School of Materials and Metallurgy, University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-08-15

    Cast iron is widely used in fields such as the transport and heavy industries. For parts where contact damage is expected to occur, it is necessary to understand the friction and wear characteristics of cast iron. In this study, we use cast iron plates as the specimens to investigate their friction and wear characteristics. We perform various experiments using a reciprocating type tribotester. We assess the frictional characteristics by analyzing the friction coefficient values that were obtained during the sliding tests. We observe the wear surfaces of cast iron and steel balls using a scanning electron microscope, confocal microscope, and 3D profiler. We investigate the friction and wear characteristics of cast iron by injecting sand and alumina particles having various sizes. Furthermore, we estimate the effect of temperature on the friction and wear characteristics. The results obtained are expected to aid in the understanding of the tribological characteristics of cast iron in industry.

  9. Fretting wear characteristic tests of X2-GEN midgrid for SMART under a FIV rod trace

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ho; Lee, Kang Hee; Kim, Jae Yong; Kim, Hyung Kyu [KAERI, Daejeon (Korea, Republic of)

    2011-12-15

    The KEPCO Nuclear Fuel Co. requested the fretting wear characteristic tests of a X2-GEN midgrid under a FIV rod trace at room temperature air. The following results were obtained for the fretting wear test. {center_dot} Fretting wear tests under a FIV rod trace Based on the result of the fretting wear tests of the X2-GEN and 17ACE7 1x1 mid-grid under a FIV rod trace, X2-GEN mid-grid showed a slightly severe wear volume rather than 17ACE7 spring. But, maximum wear depth shows an opposite behavior. This is due to spring shape effect. The fretting wear mechanisms at each mid-grid were influenced by each spring shape, that are depended on the different impacting behavior under a FIV rod motion. Up to 5x105 cycles, wear characteristics of each mid-grid shows a relatively similar wear rate. Consequently, it is necessary to further study for examining exact fretting wear behavior under a FIV rod tra

  10. A study on erosive wear behavior of HVOF sprayed nanostructured WC-CoCr coatings

    International Nuclear Information System (INIS)

    Thakur, Lalit; Arora, Navneet

    2013-01-01

    WC-CoCr cermet coatings were deposited on stainless steel substrate using high-velocity oxy-fuel (HVOF) thermal spray process. The coatings were developed with two different thermal spray powders: one has WC grains of conventional micron size and the other is composed of nanosized (near-nanostructured) grains. HVOF spraying was assisted with in-flight particle temperature and velocity measurement system to control the process parameters that have resulted in quality coatings. Cavitation erosion testing was performed using a vibratory test apparatus based on ASTM standard G32-98. Surface morphology of powders and coatings was examined using the FESEM images, and phase identification was performed by XRD analysis. The erosion behavior of coatings and mechanism of material removal was discussed by examining the microstructure images of worn-out surfaces. WC-CoCr cermet coating deposited with nanosized WC grains exhibited higher cavitation erosion resistance as compared to conventional coating.

  11. A study on erosive wear behavior of HVOF sprayed nanostructured WC-CoCr coatings

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Lalit; Arora, Navneet [Indian Institute of Technology Roorkee, Roorkee (India)

    2013-05-15

    WC-CoCr cermet coatings were deposited on stainless steel substrate using high-velocity oxy-fuel (HVOF) thermal spray process. The coatings were developed with two different thermal spray powders: one has WC grains of conventional micron size and the other is composed of nanosized (near-nanostructured) grains. HVOF spraying was assisted with in-flight particle temperature and velocity measurement system to control the process parameters that have resulted in quality coatings. Cavitation erosion testing was performed using a vibratory test apparatus based on ASTM standard G32-98. Surface morphology of powders and coatings was examined using the FESEM images, and phase identification was performed by XRD analysis. The erosion behavior of coatings and mechanism of material removal was discussed by examining the microstructure images of worn-out surfaces. WC-CoCr cermet coating deposited with nanosized WC grains exhibited higher cavitation erosion resistance as compared to conventional coating.

  12. Dynamic Characteristics of Steam Generator Tubes with Defect due to Wear

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sangjin; Rhee, Huinam [Sunchon National Univ., Sunchon (Korea, Republic of); Yoon, Doo Byung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    These defects may affect the dynamic characteristics of tubes, and therefore, the vibrational behavior of the tube due to flow-induced loads can be varied. Change in the vibrational response of a tube may result in different wear characteristics from the design condition, which must be checked for both safety and economic point of view. This paper deals with the study on the effect of wears or cracks on the dynamic characteristics of steam generator tubes using finite element analysis. In this paper the effect of defects on the surface due to wear on the variation of dynamic characteristics of steam generator tubes was studied using the finite element analysis. The changes of natural frequencies and mode shapes can directly affect the flow-induced vibration response characteristics, therefore, they must be evaluated appropriately. The results in this study can be a good basis to estimate the FIV characteristics of the steam generator tubes having defects such as wear or crack.

  13. Turbulence induced Fretting-wear characteristics of steam generator helical tubes

    International Nuclear Information System (INIS)

    Jhung, Myung Jo; Jo, Jong Chull; Kim, Hho Jung; Yune, Young Gill; Yu, Seon Oh

    2005-01-01

    This study addresses safety assessment of the potential for fretting-wear damages on steam generator helical tubes due to turbulence-induced vibration in operating nuclear power plants. To get the natural frequency, corresponding mode shape and participation factor, modal analyses are performed for helical type tubes with various conditions. Special emphases are put on the effects of coil diameter and the number of turns on the modal and fretting wear characteristics of tubes. Also, investigated are the effects of external pressure on the tube modal characteristics as well as the effects of turbulence induced vibration on the fretting-wear characteristics of tubes

  14. Wear Process Analysis of the Polytetrafluoroethylene/Kevlar Twill Fabric Based on the Components’ Distribution Characteristics

    Directory of Open Access Journals (Sweden)

    Gu Dapeng

    2017-12-01

    Full Text Available Polytetrafluoroethylene (PTFE/Kevlar fabric or fabric composites with excellent tribological properties have been considered as important materials used in bearings and bushing, for years. The components’ (PTFE, Kevlar, and the gap between PTFE and Kevlar distribution of the PTFE/Kevlar fabric is uneven due to the textile structure controlling the wear process and behavior. The components’ area ratio on the worn surface varying with the wear depth was analyzed not only by the wear experiment, but also by the theoretical calculations with our previous wear geometry model. The wear process and behavior of the PTFE/Kevlar twill fabric were investigated under dry sliding conditions against AISI 1045 steel by using a ring-on-plate tribometer. The morphologies of the worn surface were observed by the confocal laser scanning microscopy (CLSM. The wear process of the PTFE/Kevlar twill fabric was divided into five layers according to the distribution characteristics of Kevlar. It showed that the friction coefficients and wear rates changed with the wear depth, the order of the antiwear performance of the previous three layers was Layer III>Layer II>Layer I due to the area ratio variation of PTFE and Kevlar with the wear depth.

  15. Wear Characteristics of Ceramic Coating Materials by Plasma Spray under the Lubricative Environment

    International Nuclear Information System (INIS)

    Kim, Chang Ho

    2001-02-01

    This paper is to investigate the wear behaviors of two types of ceramics, Al 2 O 3 and TiO 2 , by coated plasma thermal spray method under the lubricative environment. The lubricative environments are grease fluids, a general hydraulic fluids, and bearing fluids. The wear testing machine used a pin on disk type. Wear characteristics, which were friction force, friction coefficient and the specific wear rate, according to the lubricative environments were obtained at the four kinds of load, and the sliding velocity is 0.2m/sec. After the wear experiments, the wear surfaces of the each test specimen were observed by a scanning electronic microscope. The obtained results are as follows. : 1. The friction coefficients of TiO 2 coating materials are 0.11 ∼ 0.16 range and those of Al 2 O 3 are 0.24 ∼ 0.39. The friction coefficient of two coating materials is relative to the hardness of these materials. 2. The friction coefficient of TiO 2 coating materials in three lubricative environments is almost same to each other in spite of changing of applied loads. 3. The friction coefficient of Al 2 O 3 coating materials is more large in low load than high load. And the friction coefficient in grease is more large than a general hydraulic and bearing fluids had almost same friction coefficient. 4. The specific wear rate in TiO 2 is greatly increasing according to change the applied loads, but that in Al 2 O 3 is slightly. And the wear in grease is the least among three lubricating environments. 5. On the wear mechanism by SEM image observation, the wear of Al 2 O 3 is adhesive wear and TiO 3 is abrasive wear

  16. Analytical approximation of the erosion rate and electrode wear in micro electrical discharge machining

    International Nuclear Information System (INIS)

    Kurnia, W; Tan, P C; Yeo, S H; Wong, M

    2008-01-01

    Theoretical models have been used to predict process performance measures in electrical discharge machining (EDM), namely the material removal rate (MRR), tool wear ratio (TWR) and surface roughness (SR). However, these contributions are mainly applicable to conventional EDM due to limits on the range of energy and pulse-on-time adopted by the models. This paper proposes an analytical approximation of micro-EDM performance measures, based on the crater prediction using a developed theoretical model. The results show that the analytical approximation of the MRR and TWR is able to provide a close approximation with the experimental data. The approximation results for the MRR and TWR are found to have a variation of up to 30% and 24%, respectively, from their associated experimental values. Since the voltage and current input used in the computation are captured in real time, the method can be applied as a reliable online monitoring system for the micro-EDM process

  17. Synthesis and Study on Effect of Parameters on Dry Sliding Wear Characteristics of AL-SI Alloys

    Directory of Open Access Journals (Sweden)

    Francis Uchenna OZIOKO

    2012-08-01

    Full Text Available The effect of parameters on dry sliding wear characteristics of Al-Si alloys was studied. Aluminium-silicon alloys containing 7%, 12% and 14% weight of silicon were synthesized using casting method. Dry sliding wear characteristics of sample were studied against a hardened carbon steel (Fe-2.3%Cr-0.9%C using a pin-on-disc. Observations were recorded keeping two parameters (sliding distance, sliding speed and load constant against wear at room temperature. Microstructural characterization was done using optical microscope (OM and scanning electron microscope (SEM. Hardness and wear characteristics of different samples have shown near uniform behaviour. The wear rate decreased when the percentage of silicon increases. Wear was observed to increase at higher applied load, higher sliding speed and higher sliding distance. The wear characteristics of Al-14%Si was observed superior to those of Al-7%Si and Al-12%Si due to the degree of refinement of their eutectic silicon.

  18. A statistical analysis on erosion wear behaviour of A356 alloy reinforced with in situ formed TiB2 particles

    International Nuclear Information System (INIS)

    Kumar, S.; Subramanya Sarma, V.; Murty, B.S.

    2008-01-01

    Solid particle erosion wear behaviour of A356 and A356/TiB 2 in situ composites has been studied. A356 alloy reinforced with in situ TiB 2 particles was fabricated by the reaction of halide salts with aluminium melt and the formation of Al 3 Ti brittle phase is completely suppressed. The composites show good grain refinement of α-Al and modification of eutectic Si. These in situ composites show high hardness and better erosion resistance than the base alloy. Though the sizes of in situ formed TiB 2 reinforcement particles are smaller than the erodent SiC particles, TiB 2 particles are able to effectively resist the erodent particles. Design of experiment has been used to run the solid particle erosion experiment. An attempt has also been made to develop a mathematical model by using regression analysis. Analysis of variance (ANOVA) technique is applied to check the validity of the developed model. Student's t-test is utilized to find out the significance of factors. The wear mechanism has been studied by analyzing the surface of the worn specimen using scanning electron microscopy and energy dispersive X-ray microanalysis

  19. Dependence of sputtering erosion on fuel-pellet characteristics

    International Nuclear Information System (INIS)

    Bohachevsky, I.O.; Hafer, J.F.

    1977-11-01

    Conceptual designs of fusion reactors operating on the principle of inertial confinement require that the dependence of cavity-wall erosion on fuel-pellet energy yield, its mass, and representative atomic number be known. A simple approximate model of sputtering erosion is presented and explicit formulas are derived that express the total amount of eroded wall material in terms of the above three parameters

  20. Characteristic Asphalt Concrete Wearing Course (ACWC) Using Variation Lime Filler

    Science.gov (United States)

    Permana, R. A.; Pramesti, F. P.; Setyawan, A.

    2018-03-01

    This research use of lime filler Sukaraja expected add durability layers of concrete pavement is asphalt damage caused by the weather and load traffic. This study attempts to know how much value characteristic Marshall on a mixture of concrete asphalt using lime filler. This research uses experimental methods that is with a pilot to get results, thus will look filler utilization lime on construction concrete asphalt variation in filler levels 2 %, 3 %, 4 %.The results showed that the use of lime filler will affect characteristic a mixture of concrete asphalt. The more filler chalk used to increase the value of stability. On the cretaceous filler 2 % value of stability is 1067,04 kg. When lime filler levels added to the levels of filler 4 %, the value of stability increased to 1213,92 kg. The flexibility increased the number of filler as levels lime 2 % to 4 % suggests that are conducted more stiff mix.

  1. Microstructure and erosion characteristic of nodular cast iron surface modified by tungsten inert gas

    International Nuclear Information System (INIS)

    Abboud, Jaafar Hadi

    2012-01-01

    Highlights: ► Local surface melting. ► Significant improvement in erosion resistance. ► The ductile behaviour was found. -- Abstract: The surface of nodular cast iron has been melted and rapidly solidified by Tungsten Inert Gas (TIG) process to produce a chilled structure of high hardness and better erosion resistance. Welding currents of magnitude 100, 150, and 200 A at a constant voltage of 72 have been used to melt the surface of nodular cast iron. Microstructural characterization, hardness measurements, and erosion wear tests have been performed on these modified surfaces as well as on the untreated material. Microstructural characterization has shown that surface melting resulted in complete or partial dissolution of the graphite nodules and resolidification of primary austenite dendrites, which undergo further decomposition into ferrite and cementite, and interdendritic of acicular eutectic; their microhardness measured across the melted depth ranged between 600 and 800 Hv. The scale of the dendrites and the interdendritic eutectic became coarser when a higher current is used. The results also indicated that remelting process by TIG improved erosion resistance by three to four times. Eroded surface observations of the as-received and TIG melted samples showed a ductile behavior with a maximum erosion rate at 30°. The fine microstructures obtained by the rapid cooling and the formation of a large amount of eutectic cementite instead of the graphite have contributed greatly to the plastic flow and consequently to the better erosion resistance of the TIG surface melted samples.

  2. Wear characteristics of polished and glazed lithium disilicate ceramics opposed to three ceramic materials.

    Science.gov (United States)

    Saiki, Osamu; Koizumi, Hiroyasu; Akazawa, Nobutaka; Kodaira, Akihisa; Okamura, Kentaro; Matsumura, Hideo

    2016-01-01

    This study compared the wear characteristics of a heat-pressed lithium disilicate ceramic material opposed to feldspathic porcelain, a lithium disilicate glass ceramic, and zirconia materials. Ceramic plate specimens were prepared from feldspathic porcelain (EX-3 nA1B), lithium disilicate glass ceramics (e.max CAD MO1/C14), and zirconia (Katana KT 10) and then ground or polished. Rounded rod specimens were fabricated from heat-pressed lithium disilicate glass ceramic (e.max press LT A3) and then glazed or polished. A sliding wear testing apparatus was used for wear testing. Wear of glazed rods was greater than that of polished rods when they were abraded with ground zirconia, ground porcelain, polished porcelain, or polished lithium disilicate ceramics. For both glazed and polished rods, wear was greater when the rods were abraded with ground plates. The findings indicate that application of a polished surface rather than a glazed surface is recommended for single restorations made of heat-pressed lithium disilicate material. In addition, care must be taken when polishing opposing materials, especially those used in occlusal contact areas. (J Oral Sci 58, 117-123, 2016).

  3. Use of an additive in biofuel to evaluate emissions, engine component wear and lubrication characteristics

    International Nuclear Information System (INIS)

    Kalam, M.A.; Majsuki, H.H.

    2003-01-01

    This paper presents the results of experiments carried out to evaluate the effect of adding an anticorrosion additive to blended biofuel and lubricating oil on emissions, engine component wear and lubrication characteristics. The blended biofuels consist of 7.5 and 15 per cent palm olein (PO) with ordinary diesel oil (OD). Pure OD was used for comparison purposes. Exhaust emission gases such as NO x , CO and hydrocarbons (HCs) were measured by an exhaust emission analyser for engine operation on 50 per cent throttle at speeds of 800-3600 r/min. To measure engine component wear and lubricating oil characteristics, the engine was operated at 50 per cent throttle at a speed of 2000 r/min for a period of 100 h with each of the fuel samples. The same lubricating oil, conventional SAE 40, was used in all the fuels. A multielement oil analyser (MOA) was used to measure the increase in wear of metals (Fe, Cu, Al, Pd) and the decrease in lubricating oil additives (Zn, Ca) in the lubricating oil used. An ISL automatic Houillon viscometer (ASTM D445) and potentiometric titration (ASTM D2896) were used to measure viscosity and total base number (TBN) respectively. The results show that the addition of anticorrosion additive with biofuel and lubricating oil improves the emission and engine wear characteristics; both the exhaust emission gases (NO x , CO and HCs) and the wear of metals (Fe, Cu, Al and Pd) decrease with the blended fuels in comparison with the base fuel OD. Detailed results, including engine brake power, are discussed. (Author)

  4. Using Cesium-137 technique to study the characteristics of different aspect of soil erosion in the Wind-water Erosion Crisscross Region on Loess Plateau of China

    International Nuclear Information System (INIS)

    Li Mian; Li Zhanbin; Liu Puling; Yao Wenyi

    2005-01-01

    The most serious soil erosion on Loess Plateau exists in the Wind-water Erosion Crisscross Region. In the past 20 years, the types and intensity of soil erosion and its temporal and spatial distribution were studied, but studies on the difference of soil erosion between slope aspects and slope positions in this area have no report. However, it is very important to analyze and evaluate quantitatively the characteristics of different aspects and positions of soil loss for the prevention and treatment of soil erosion in this area. The spatial pattern of net soil loss on 4 downslope transects in four aspects (east, west, south and north) on a typical Mao (round loess mound) in Liudaogou catchment in Wind-water Erosion Crisscross Region was measured in 2000 using the resident cesium-137 deficit technique. The purposes of this investigation were undertaken to determine whether or not 137 Cs measurement would give a useful indication of the extent of soil loss and their characteristics from cultivated hillsides in different slope aspect and slope position in the study area. The results showed that the difference of soil erosion in different aspect was significant and the erosion rate was in this order: north>east>south>west. Compared with other areas, the difference of erosion rate between north hillside and south hillside was on the contrary, and the possible explanations could be the effect of wind erosion. Also, the percentage of wind erosion was estimated to be at least larger than 18% of total soil loss by comparing the difference of erosion amount in south hillside and north hillside. The erosion rates on different slope positions in all aspects were also different, the highest net soil loss occurred in the lower slope position, and the upper and middle slope positions were slight. The general trend of net soil loss on sloping surface was to increase in fluctuation with increasing downslope distance

  5. Using Cesium-137 technique to study the characteristics of different aspect of soil erosion in the Wind-water Erosion Crisscross Region on Loess Plateau of China

    Energy Technology Data Exchange (ETDEWEB)

    Li Mian E-mail: hnli-mian@163.com; Li Zhanbin; Liu Puling; Yao Wenyi

    2005-01-01

    The most serious soil erosion on Loess Plateau exists in the Wind-water Erosion Crisscross Region. In the past 20 years, the types and intensity of soil erosion and its temporal and spatial distribution were studied, but studies on the difference of soil erosion between slope aspects and slope positions in this area have no report. However, it is very important to analyze and evaluate quantitatively the characteristics of different aspects and positions of soil loss for the prevention and treatment of soil erosion in this area. The spatial pattern of net soil loss on 4 downslope transects in four aspects (east, west, south and north) on a typical Mao (round loess mound) in Liudaogou catchment in Wind-water Erosion Crisscross Region was measured in 2000 using the resident cesium-137 deficit technique. The purposes of this investigation were undertaken to determine whether or not {sup 137}Cs measurement would give a useful indication of the extent of soil loss and their characteristics from cultivated hillsides in different slope aspect and slope position in the study area. The results showed that the difference of soil erosion in different aspect was significant and the erosion rate was in this order: north>east>south>west. Compared with other areas, the difference of erosion rate between north hillside and south hillside was on the contrary, and the possible explanations could be the effect of wind erosion. Also, the percentage of wind erosion was estimated to be at least larger than 18% of total soil loss by comparing the difference of erosion amount in south hillside and north hillside. The erosion rates on different slope positions in all aspects were also different, the highest net soil loss occurred in the lower slope position, and the upper and middle slope positions were slight. The general trend of net soil loss on sloping surface was to increase in fluctuation with increasing downslope distance.

  6. Fretting-wear characteristics of steam generator tubes contacting with foreign object

    International Nuclear Information System (INIS)

    Jo, Jong Chull; Jhung, Myung Jo; Kim, Woong Sik; Kim, Hho Jung

    2003-01-01

    Fretting-wear characteristics of steam generator tubes contacting with foreign object has been investigated in this study. The operating steam generator shell-side flow field conditions are obtained from three-dimensional steam generator flow calculation using a well-validated steam generator thermal-hydraulic analysis computer code. Modal analyses are performed for the finite element modelings of tubes to get the natural frequency, corresponding mode shape and participation factor. The wear rate of a steam generator tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted. In addition, the effects of internal pressure and flow velocity on the remaining life of the tube are discussed in this paper

  7. Microstructure and wear characteristics on Al alloy matrix composite reinforced with Ni perform

    Energy Technology Data Exchange (ETDEWEB)

    Park, Won Jo; Park, Cheol Hong; Kim, Hyung Jin; Huh, Sun Chul [Gyeongsang National University, Tongyeong, (Korea, Republic of)

    2012-06-15

    Al based composite reinforced with Nickel is used for diesel engine piston, because the thermal properties, strength and corrosion resistant are for better than Al alloy alone. For processing, the intermetallic compounds of Ni and Al improves wear resistance due to its high hardness. Existing process methods for MMC (metal matrix composite) using preform were manufactured under high-pressure. However, this causes deformation of the preform or weaknesses in the completed MMC. Low-pressure infiltration can prevent these problems, and there is an advantage of cost reduction in of production with small-scale of production equipment. In this study, the microstructure and wear characteristics of Al-based composite with Ni preform as reinforcement with low-pressure infiltration was analyzed.

  8. Saliva and dental erosion

    Directory of Open Access Journals (Sweden)

    Marília Afonso Rabelo Buzalaf

    2012-10-01

    Full Text Available Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective: This review discusses the role of salivary factors on the development of dental erosion. Material and Methods: A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results: Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions: Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

  9. Saliva and dental erosion.

    Science.gov (United States)

    Buzalaf, Marília Afonso Rabelo; Hannas, Angélicas Reis; Kato, Melissa Thiemi

    2012-01-01

    Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. This review discusses the role of salivary factors on the development of dental erosion. A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

  10. Sliding wear characteristics of carburized steels and thermally refined steels implanted with nitrogen ions

    International Nuclear Information System (INIS)

    Terashima, Keiichi; Koda, Hiroyuki; Takeuchi, Eiichi.

    1995-01-01

    In order to concretely examine the application of surface reforming by ion implantation, nitrogen ion implantation was applied to the thermally refined steels S45C and SCM440 and the carburized steel SCM415, which are high versatile steels for mechanical structures, and their friction and wear characteristics were examined. The results are summarized as follows. In the surface-reformed material, in which nitrogen was implanted for the purpose of improving the seizure durability of the carburized steel, the load-frictional coefficient curve in lubricated sliding friction was similar to that of the material without implantation, but it was recognized that the load at which seizure occurred reached 2000 kgf or more, and as the amount of implantation was more, the material withstood higher load. In the lubricated sliding friction using a pin-ring type wear testing machine of the thermally refined steels and those to which implantation was applied, it was recognized that the specific wear amount was less in the implanted steels than in those without implantation. The results of the analysis of the implanted surface layers and the friction surfaces are reported. (K.I.)

  11. Microstructural and wear characteristics of cobalt free, nickel base intermetallic alloy deposited by laser cladding

    International Nuclear Information System (INIS)

    Awasthi, Reena; Kumar, Santosh; Viswanadham, C.S.; Srivastava, D.; Dey, G.K.; Limaye, P.K.

    2011-01-01

    This paper describes the microstructural and wear characteristics of Ni base intermetallic hardfacing alloy (Tribaloy-700) deposited on stainless steel-316 L substrate by laser cladding technique. Cobalt base hardfacing alloys have been most commonly used hardfacing alloys for application involving wear, corrosion and high temperature resistance. However, the high cost and scarcity of cobalt led to the development of cobalt free hardfacing alloys. Further, in the nuclear industry, the use of cobalt base alloys is limited due to the induced activity of long lived radioisotope 60 Co formed. These difficulties led to the development of various nickel and iron base alloys to replace cobalt base hardfacing alloys. In the present study Ni base intermetallic alloy, free of Cobalt was deposited on stainless steel- 316 L substrate by laser cladding technique. Traditionally, welding and thermal spraying are the most commonly employed hardfacing techniques. Laser cladding has been explored for the deposition of less diluted and fusion-bonded Nickel base clad layer on stainless steel substrate with a low heat input. The laser cladding parameters (Laser power density: 200 W/mm 2 , scanning speed: 430 mm/min, and powder feed rate: 14 gm/min) resulted in defect free clad with minimal dilution of the substrate. The microstructure of the clad layer was examined by Optical microscopy, Scanning electron microscopy, with energy dispersive spectroscopy. The phase analysis was performed by X-ray diffraction technique. The clad layer exhibited sharp substrate/clad interface in the order of planar, cellular, and dendritic from the interface upwards. Dilution of clad with Fe from substrate was very low passing from ∼ 15% at the interface (∼ 40 μm) to ∼ 6% in the clad layer. The clad layer was characterized by the presence of hexagonal closed packed (hcp, MgZn 2 type) intermetallic Laves phase dispersed in the eutectic of Laves and face centered cubic (fcc) gamma solid solution. The

  12. Diode-rectified multiphase AC arc for the improvement of electrode erosion characteristics

    Science.gov (United States)

    Tanaka, Manabu; Hashizume, Taro; Saga, Koki; Matsuura, Tsugio; Watanabe, Takayuki

    2017-11-01

    An innovative multiphase AC arc (MPA) system was developed on the basis of a diode-rectification technique to improve electrode erosion characteristics. Conventionally, electrode erosion in AC arc is severer than that in DC arc. This originated from the fact that the required properties for the cathode and anode are different, although an AC electrode works as the cathode and the anode periodically. To solve this problem, a separation of AC electrodes into pairs of thoriated tungsten cathode and copper anode by diode-rectification was attempted. A diode-rectified multiphase AC arc (DRMPA) system was then successfully established, resulting in a drastic improvement of the erosion characteristics. The electrode erosion rate in the DRMPA was less than one-third of that in the conventional MPA without the diode rectification. In order to clarify its erosion mechanism, electrode phenomena during discharge were visualized by a high-speed camera system with appropriate band-pass filters. Fluctuation characteristics of the electrode temperature in the DRMPA were revealed.

  13. Tooth wear

    OpenAIRE

    Tušek Ivan; Tušek Jasmina

    2014-01-01

    Tooth wear is the loss of dental hard tissue that was not caused by decay and represents a common clinical problem of modern man. In the etiology of dental hard tissue lesions there are three dominant mechanisms that may act synergistically or separately:friction (friction), which is caused by abrasion of exogenous, or attrition of endogenous origin, chemical dissolution of dental hard tissues caused by erosion, occlusal stress created by compression and flexion and tension that leads to toot...

  14. Tooth wear

    Directory of Open Access Journals (Sweden)

    Tušek Ivan

    2014-01-01

    Full Text Available Tooth wear is the loss of dental hard tissue that was not caused by decay and represents a common clinical problem of modern man. In the etiology of dental hard tissue lesions there are three dominant mechanisms that may act synergistically or separately:friction (friction, which is caused by abrasion of exogenous, or attrition of endogenous origin, chemical dissolution of dental hard tissues caused by erosion, occlusal stress created by compression and flexion and tension that leads to tooth abfraction and microfracture. Wear of tooth surfaces due to the presence of microscopic imperfections of tooth surfaces is clinically manifested as sanding veneers. Tribology, as an interdisciplinary study of the mechanisms of friction, wear and lubrication at the ultrastructural level, has defined a universal model according to which the etiopathogenesis of tooth wear is caused by the following factors: health and diseases of the digestive tract, oral hygiene, eating habits, poor oral habits, bruxism, temporomandibular disorders and iatrogenic factors. Attrition and dental erosion are much more common in children with special needs (Down syndrome. Erosion of teeth usually results from diseases of the digestive tract that lead to gastroesophageal reflux (GER of gastric juice (HCl. There are two basic approaches to the assessment of the degree of wear and dental erosion. Depending on the type of wear (erosion, attrition, abfraction, the amount of calcium that was realised during the erosive attack could be determined qualitatively and quantitatively, or changes in optical properties and hardness of enamel could be recorded, too. Abrasion of teeth (abrasio dentium is the loss of dental hard tissue caused by friction between the teeth and exogenous foreign substance. It is most commonly provoked by prosthetic dentures and bad habits, while its effect depends on the size of abrasive particles and their amount, abrasive particle hardness and hardness of tooth

  15. Decay characteristics and erosion-related transport of glyphosate in Chinese loess soil under field conditions

    NARCIS (Netherlands)

    Yang, X.; Wang, Fei; Martins Bento, Celia; Meng, L.; Dam, van R.C.J.; Mol, J.G.J.; Liu, Guobin; Ritsema, C.J.; Geissen, V.

    2015-01-01

    The decay characteristics and erosion-related transport of glyphosate and aminomethylphosphonic acid (AMPA) were monitored for 35 d at different slope gradients and rates of application in plots with loess soil on the Loess Plateau, China. The initial glyphosate decayed rapidly (half-life of 3.5 d)

  16. Implementation of palm biodiesel based on economic aspects, performance, emission, and wear characteristics

    International Nuclear Information System (INIS)

    Mosarof, M.H.; Kalam, M.A.; Masjuki, H.H.; Ashraful, A.M.; Rashed, M.M.; Imdadul, H.K.; Monirul, I.M.

    2015-01-01

    Highlights: • Global environmental protection of using alternative fuel. • Economic aspects of palm oil biodiesel in Malaysia. • Tribological characteristics of palm oil biodiesel in engine components. • Engine performance and emission of palm oil biodiesel. • Effect of temperature on density and kinematic viscosity for various biodiesel. - Abstract: The high cost of energy supplies and the growing concern over the dependency on fossil fuels have impelled many countries to search for renewable and alternative energy sources. The extensive use of fossil fuels for transportation and power generation all over the world have caused the supply of fossil fuels to continuously decrease and have aggravated environmental pollution. Searching for alternative fuels has become imperative to reduce pollution and address the problems on fossil fuels. Vegetable oil fuels, such as palm oil biodiesel, serve as alternative forms of energy and are currently being studied, particularly as a diesel fuel substitute. The purpose of this study is to review the potential of palm oil as an energy source and alternative diesel fuel in terms of its performance, environmental impact, wear characteristics, and economic considerations. Compared with other vegetable oils, palm oil is a relatively sustainable, environment-friendly, less expensive, and economically beneficial potential source of energy. Palm oil plantation and production is a major industry in Malaysia, contributing to the economic growth and development of the country. The properties of palm oil biodiesel, namely, high oxidation stability, good cold properties, cetane number, and higher viscosity, makes it a suitable diesel substitute. Compared with other vegetable oils and petroleum diesel fuels, palm oil is associated with better engine performance, higher specific fuel consumption, and shorter ignition delay. Use of palm oil also reduces exhaust emission of hydrocarbon, carbon monoxide, carbon dioxide, and smoke, but

  17. Distinguishing and diagnosing contemporary and conventional features of dental erosion.

    Science.gov (United States)

    Bassiouny, Mohamed A

    2014-01-01

    The vast number and variety of erosion lesions encountered today require reconsideration of the traditional definition. Dental erosion associated with modern dietary habits can exhibit unique features that symbolize a departure from the decades-old conventional image known as tooth surface loss. The extent and diversity of contemporary erosion lesions often cause conflicting diagnoses. Specific examples of these features are presented in this article. The etiologies, genesis, course of development, and characteristics of these erosion lesions are discussed. Contemporary and conventional erosion lesions are distinguished from similar defects, such as mechanically induced wear, carious lesions, and dental fluorosis, which affect the human dentition.

  18. Predicting wear of hydrotransport pipelines in oil sand slurries

    Energy Technology Data Exchange (ETDEWEB)

    Been, J.; Lu, B.; Wolodko, J. [Alberta Research Council, Edmonton, AB (Canada); Kiel, D. [Coanda Research and Development Corp., Burnaby, BC (Canada)

    2008-07-01

    An overview of erosion and corrosion methods and techniques was presented. Wear to pipelines is influenced by slurry flow and chemistry; solids loading; and electrochemical interactions. While several experimental techniques have been developed to rank the performance of different pipeline materials, experiments do not currently provide accurate quantitative prediction of pipeline wear in the field. Rotating cylinder electrodes (RCE) and jet impingement methods are used to study the effect of flow velocity on corrosion rate. Slurry pot erosion-corrosion testers are used to rank materials for use in more dilute, less turbulent slurries. Coriolois slurry erosion testers are used to rank the erosion resistance of different pipeline materials. A pilot-scale flow loop is now being constructed by the Alberta Research Council (ARC) in order to replicate wet erosion phenomena in oil sands applications. The flow loop will be used to simulate the field conditions of oil sands pipelines and develop predictive wear data and models. Coulombic shear stress and characteristic wall velocities have been determined using a 2-layer model designed to represent flow as 2 distinct layers. To date, the flow loop pilot study has demonstrated that wear rates in smaller diameter flow loops are not significantly different than larger diameter field installations. Preliminary calculations have demonstrated that the flow loop can be used to accurately simulate the hydrodynamics and wear typically experienced in field slurry flows. 67 refs., 2 tabs., 7 figs.

  19. Erosion characteristics and horizontal variability for small erosion depths in the Sacramento-San Joaquin River Delta, California, USA

    Science.gov (United States)

    Schoellhamer, David H.; Manning, Andrew J.; Work, Paul A.

    2017-01-01

    Erodibility of cohesive sediment in the Sacramento-San Joaquin River Delta (Delta) was investigated with an erosion microcosm. Erosion depths in the Delta and in the microcosm were estimated to be about one floc diameter over a range of shear stresses and times comparable to half of a typical tidal cycle. Using the conventional assumption of horizontally homogeneous bed sediment, data from 27 of 34 microcosm experiments indicate that the erosion rate coefficient increased as eroded mass increased, contrary to theory. We believe that small erosion depths, erosion rate coefficient deviation from theory, and visual observation of horizontally varying biota and texture at the sediment surface indicate that erosion cannot solely be a function of depth but must also vary horizontally. We test this hypothesis by developing a simple numerical model that includes horizontal heterogeneity, use it to develop an artificial time series of suspended-sediment concentration (SSC) in an erosion microcosm, then analyze that time series assuming horizontal homogeneity. A shear vane was used to estimate that the horizontal standard deviation of critical shear stress was about 30% of the mean value at a site in the Delta. The numerical model of the erosion microcosm included a normal distribution of initial critical shear stress, a linear increase in critical shear stress with eroded mass, an exponential decrease of erosion rate coefficient with eroded mass, and a stepped increase in applied shear stress. The maximum SSC for each step increased gradually, thus confounding identification of a single well-defined critical shear stress as encountered with the empirical data. Analysis of the artificial SSC time series with the assumption of a homogeneous bed reproduced the original profile of critical shear stress, but the erosion rate coefficient increased with eroded mass, similar to the empirical data. Thus, the numerical experiment confirms the small-depth erosion hypothesis. A linear

  20. Solid particle erosion of polymers and composites

    Science.gov (United States)

    Friedrich, K.; Almajid, A. A.

    2014-05-01

    After a general introduction to the subject of solid particle erosion of polymers and composites, the presentation focusses more specifically on the behavior of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites under such loadings, using different impact conditions and erodents. The data were analyzed on the basis of a newly defined specific erosive wear rate, allowing a better comparison of erosion data achieved under various testing conditions. Characteristic wear mechanisms of the CF/PEEK composites consisted of fiber fracture, matrix cutting and plastic matrix deformation, the relative contribution of which depended on the impingement angles and the CF orientation. The highest wear rates were measured for impingement angles between 45 and 60°. Using abrasion resistant neat polymer films (in this case PEEK or thermoplastic polyurethane (TPU) ones) on the surface of a harder substrate (e.g. a CF/PEEK composite plate) resulted in much lower specific erosive wear rates. The use of such polymeric films can be considered as a possible method to protect composite surfaces from damage caused by minor impacts and erosion. In fact, they are nowadays already successfully applied as protections for wind energy rotor blades.

  1. Variability of Rainfall Erosivity and Erosivity Density in the Ganjiang River Catchment, China: Characteristics and Influences of Climate Change

    Directory of Open Access Journals (Sweden)

    Xianghu Li

    2018-02-01

    Full Text Available Soil erosion is one of the most critical environmental hazards in the world. Understanding the changes in rainfall erosivity (RE and erosivity density (ED, as well as their affecting factors, at local and catchment scales in the context of climate warming is an important prerequisite of soil erosion prevention and soil loss risk assessment. The present study identified the variability and trends of RE and ED in terms of both time and space in the Ganjiang River catchment over the period of 1960–2012, and also analyzed and discussed the impact of climate change. The results show that RE and ED in the catchment had great monthly variations and high year-to-year variability. Both presented long-term increasing trends over the entire study period. The highest RE and ED were observed in June and in the eastern and northeast parts of the catchment, which indicated that June was the most susceptible month for soil erosion in this area and the lower reaches of the Ganjiang River was the riskiest area for soil erosion. Finally, the East Asian summer monsoon and climate change were highly correlated with changes in RE and ED.

  2. Wear Characteristics of Hybrid Composites Based on Za27 Alloy Reinforced With Silicon Carbide and Graphite Particles

    Directory of Open Access Journals (Sweden)

    S. Mitrović

    2014-06-01

    Full Text Available The paper presents the wear characteristics of a hybrid composite based on zinc-aluminium ZA27 alloy, reinforced with silicon-carbide and graphite particles. The tested sample contains 5 vol.% of SiC and 3 vol.% Gr particles. Compocasting technique has been used to prepare the samples. The experiments were performed on a “block-on-disc” tribometer under conditions of dry sliding. The wear volumes of the alloy and the composite were determined by varying the normal loads and sliding speeds. The paper contains the procedure for preparation of sample composites and microstructure of the composite material and the base ZA27 alloy. The wear surface of the composite material was examined using the scanning electronic microscope (SEM and energy dispersive spectrometry (EDS. Conclusions were obtained based on the observed impact of the sliding speed, normal load and sliding distance on tribological behaviour of the observed composite.

  3. FEM-DEM coupling simulations of the tool wear characteristics in prestressed machining superalloy

    Directory of Open Access Journals (Sweden)

    Ruitao Peng

    2016-01-01

    Full Text Available Due to the complicated contact loading at the tool-chip interface, ceramic tool wear in prestressed machining superalloy is rare difficult to evaluate only by experimental approaches. This study aims to develop a methodology to predict the tool wear evolution by using combined FEM and DEM numerical simulations. Firstly, a finite element model for prestressed cutting is established, subsequently a discrete element model to describe the tool-chip behaviour is established based on the obtained boundary conditions by FEM simulations, finally, simulated results are experimentally validated. The predicted tool wear results show nice agreement with experiments, the simulation indicates that, within a certain range, higher cutting speed effectively results in slighter wear of Sialon ceramic tools, and deeper depth of cut leads to more serious tool wear.

  4. Characteristics of pulsed runoff-erosion events under typical rainstorms in a small watershed on the Loess Plateau of China.

    Science.gov (United States)

    Wu, Lei; Jiang, Jun; Li, Gou-Xia; Ma, Xiao-Yi

    2018-02-27

    The pulsed events of rainstorm erosion on the Loess Plateau are well-known, but little information is available concerning the characteristics of superficial soil erosion processes caused by heavy rainstorms at the watershed scale. This study statistically evaluated characteristics of pulsed runoff-erosion events based on 17 observed rainstorms from 1997-2010 in a small loess watershed on the Loess Plateau of China. Results show that: 1) Rainfall is the fundamental driving force of soil erosion on hillslopes, but the correlations of rainfall-runoff and rainfall-sediment in different rainstorms are often scattered due to infiltration-excess runoff and soil conservation measures. 2) Relationships between runoff and sediment for each rainstorm event can be regressed by linear, power, logarithmic and exponential functions. Cluster Analysis is helpful in classifying runoff-erosion events and formulating soil conservation strategies for rainstorm erosion. 3) Response characteristics of sediment yield are different in different levels of pulsed runoff-erosion events. Affected by rainfall intensity and duration, large changes may occur in the interactions between flow and sediment for different flood events. Results provide new insights into runoff-erosion processes and will assist soil conservation planning in the loess hilly region.

  5. Compressive Properties and Anti-Erosion Characteristics of Foam Concrete in Road Engineering

    Science.gov (United States)

    Li, Jinzhu; Huang, Hongxiang; Wang, Wenjun; Ding, Yifan

    2018-01-01

    To analyse the compression properties and anti-erosion characteristics of foam concrete, one dimensional compression tests were carried out using ring specimens of foam concrete, and unconfined compression tests were carried out using foam concrete specimens cured in different conditions. The results of one dimensional compression tests show that the compression curve of foam concrete has two critical points and three stages, which has significant difference with ordinary geotechnical materials such as soil. Based on the compression curve the compression modulus of each stage were determined. The results of erosion tests show that sea water has a slight influence on the long-term strength of foam concrete, while the sulphate solution has a significant influence on the long-term strength of foam concrete, which needs to pay more attention.

  6. Effect of Applied Current Density on Cavitation-Erosion Characteristics for Anodized Al Alloy.

    Science.gov (United States)

    Lee, Seung-Jun; Kim, Seong-Jong

    2018-02-01

    Surface finishing is as important as selection of material to achieve durability. Surface finishing is a process to provide surface with the desired performance and features by applying external forces such as thermal energy or stress. This study investigated the optimum supply current density for preventing from cavitation damages by applying to an anodizing technique that artificially forms on the surface an oxide coating that has excellent mechanical characteristics, such as hardness, wear resistance. Result of hardness test, the greater hardness was associated with greater brittleness, resulting in deleterious characteristics. Consequently, under conditions such as the electrolyte concentration of 10 vol.%, the processing time of 40 min, the electrolyte temperature of 10 °C, and the current density of 20 mA/cm2 were considered to be the optimum anodizing conditions for improvement of durability in seawater.

  7. Friction, wear, and erosion atlas

    CERN Document Server

    Budinski, Kenneth G

    2013-01-01

    "Fundamental aspects of concepts are explained clearly and simply…[and] are supported by illustrations and images of worn surfaces. In addition the book contains a number of appendices, which provide useful engineering information related to tribology."-Raymond G. Bayer, Tribology Consultant, USA

  8. Fabrication, microstructural characterization and wear characteristics of A380 alloy-alumina composites

    KAUST Repository

    Nurani, Sheikh Jaber

    2016-03-10

    To obtain better mechanical and tribological properties than aluminium alloys aluminium is reinforced with alumina particles making aluminium metal matrix composites. In this work scrap piston A380 alloy was used as the matrix alloy. Alumina particles were added by 5%, 10% and 15% into matrix alloy respectively to form desired composites by stir casting technique. Pin on disc wear testing machine with counter surface as steel disc of hardness HRC 32 and surface roughness of 0.62 μm was used to conduct the wear test. In result composites showed superior wear resistance property over A380 alloy. The effect of load, sliding speed and sliding distance on wear behaviour were also examined in this study. Wear mechanism was identified from the worn surface. Both optical and scanning electron microscope (SEM) of the composites was performed to determine the microstructures. Optical micrograph shows grain size decreases with addition of alumina particles. EDS analysis was performed to confirm the presence of α-Al matrix, primary Si particles and intermetallic. As a general method, phase compositions were analyzed by using a scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS). Optical microstructures were consistent with the SEM micrographs. © 2015 IEEE.

  9. Wear characteristics of current aesthetic dental restorative CAD/CAM materials: two-body wear, gloss retention, roughness and Martens hardness.

    Science.gov (United States)

    Mörmann, Werner H; Stawarczyk, Bogna; Ender, Andreas; Sener, Beatrice; Attin, Thomas; Mehl, Albert

    2013-04-01

    This study determined the two-body wear and toothbrushing wear parameters, including gloss and roughness measurements and additionally Martens hardness, of nine aesthetic CAD/CAM materials, one direct resin-based nanocomposite plus that of human enamel as a control group. Two-body wear was investigated in a computer-controlled chewing simulator (1.2 million loadings, 49N at 1.7Hz; 3000 thermocycles 5/50°C). Each of the 11 groups consisted of 12 specimens and 12 enamel antagonists. Quantitative analysis of wear was carried out with a 3D-surface analyser. Gloss and roughness measurements were evaluated using a glossmeter and an inductive surface profilometer before and after abrasive toothbrushing of machine-polished specimens. Additionally Martens hardness was measured. Statistically significant differences were calculated with one-way ANOVA (analysis of variance). Statistically significant differences were found for two-body wear, gloss, surface roughness and hardness. Zirconium dioxide ceramics showed no material wear and low wear of the enamel antagonist. Two-body wear of CAD/CAM-silicate and -lithium disilicate ceramics, -hybrid ceramics and -nanocomposite as well as direct nanocomposite did not differ significantly from that of human enamel. Temporary polymers showed significantly higher material wear than permanent materials. Abrasive toothbrushing significantly reduced gloss and increased roughness of all materials except zirconium dioxide ceramics. Gloss retention was highest with zirconium dioxide ceramics, silicate ceramics, hybrid ceramics and nanocomposites. Temporary polymers showed least gloss retention. Martens hardness differed significantly among ceramics, between ceramics and composites, and between resin composites and acrylic block materials as well. All permanent aesthetic CAD/CAM block materials tested behave similarly or better with respect to two-body wear and toothbrushing wear than human enamel, which is not true for temporary polymer CAD

  10. Theoretical and experimental investigation of wear characteristics of aluminum based metal matrix composites using RSM

    International Nuclear Information System (INIS)

    Selvi, S.; Rajasekar, E.

    2015-01-01

    The tribological properties such as wear rate, hardness of the aluminum-fly ash composite synthesized by stir casting were investigated by varying the weight % of fly ash from 5 to 20 with constant weight % of zinc and magnesium metal powder. A mathematical model was developed to predict the wear rate of aluminum metal matrix composites and the adequacy of the model was verified using analysis of variance. Scanning electron microscopy was used for the microstructure analysis which showed a uniform distribution of fly ash in the metal matrix. Energy - dispersive X-ray spectroscopy was used for the elemental analysis or chemical characterization of a sample. The results showed that addition of fly ash to aluminum based metal matrix improved both the mechanical and tribological properties of the composites. The fly ash particles improved the wear resistance of the metal matrix composites because the hardness of the samples taken increased as the fly ash content was increased.

  11. Sliding Wear Characteristics and Corrosion Behaviour of Selective Laser Melted 316L Stainless Steel

    Science.gov (United States)

    Sun, Y.; Moroz, A.; Alrbaey, K.

    2014-02-01

    Stainless steel is one of the most popular materials used for selective laser melting (SLM) processing to produce nearly fully dense components from 3D CAD models. The tribological and corrosion properties of stainless steel components are important in many engineering applications. In this work, the wear behaviour of SLM 316L stainless steel was investigated under dry sliding conditions, and the corrosion properties were measured electrochemically in a chloride containing solution. The results show that as compared to the standard bulk 316L steel, the SLM 316L steel exhibits deteriorated dry sliding wear resistance. The wear rate of SLM steel is dependent on the vol.% porosity in the steel and by obtaining full density it is possible achieve wear resistance similar to that of the standard bulk 316L steel. In the tested chloride containing solution, the general corrosion behaviour of the SLM steel is similar to that of the standard bulk 316L steel, but the SLM steel suffers from a reduced breakdown potential and is more susceptible to pitting corrosion. Efforts have been made to correlate the obtained results with porosity in the SLM steel.

  12. Erosive gastritis

    International Nuclear Information System (INIS)

    Mohammed, S.H.; Conrad, C.; Kjoergaad, J.

    1982-01-01

    Erosive gastritis is a well-defined radiologic and endoscopic entity. It is one of the common causes of upper gastrointestinal bleeding, yet it is seldom diagnosed and often confused with a number of other diseases. This communication re-emphasizes the characteristic endoscopic and radiologic features of erosive gastritis and its differential diagnosis. Two representative cases are reported. (orig.)

  13. Erosive gastritis

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, S.H.; Conrad, C.; Kjoergaad, J.

    1982-08-01

    Erosive gastritis is a well-defined radiologic and endoscopic entity. It is one of the common causes of upper gastrointestinal bleeding, yet it is seldom diagnosed and often confused with a number of other diseases. This communication re-emphasizes the characteristic endoscopic and radiologic features of erosive gastritis and its differential diagnosis. Two representative cases are reported.

  14. Scenario Studies on Effects of Soil Infiltration Rates, Land Slope, and Furrow Irrigation Characteristics on Furrow Irrigation-Induced Erosion.

    Science.gov (United States)

    Dibal, Jibrin M; Ramalan, A A; Mudiare, O J; Igbadun, H E

    2014-01-01

    Furrow irrigation proceeds under several soil-water-furrow hydraulics interaction dynamics. The soil erosion consequences from such interactions in furrow irrigation in Samaru had remained uncertain. A furrow irrigation-induced erosion (FIIE) model was used to simulate the potential severity of soil erosion in irrigated furrows due to interactive effects of infiltration rates, land slope, and some furrow irrigation characteristics under different scenarios. The furrow irrigation characteristics considered were furrow lengths, widths, and stream sizes. The model itself was developed using the dimensional analysis approach. The scenarios studied were the interactive effects of furrow lengths, furrow widths, and slopes steepness; infiltration rates and furrow lengths; and stream sizes, furrow lengths, and slopes steepness on potential furrow irrigation-induced erosion, respectively. The severity of FIIE was found to relate somewhat linearly with slope and stream size, and inversely with furrow lengths and furrow width. The worst soil erosion (378.05 t/ha/yr) was found as a result of the interactive effects of 0.65 m furrow width, 50 m furrow length, and 0.25% slope steepness; and the least soil erosion (0.013 t/ha/yr) was induced by the combined effects of 0.5 l/s, 200 m furrow length, and 0.05% slope steepness. Evidently considering longer furrows in furrow irrigation designs would be a better alternative of averting excessive FIIE.

  15. Surface runoff and soil erosion by difference of surface cover characteristics using by an oscillating rainfall simulator

    Science.gov (United States)

    Kim, J. K.; Kim, M. S.; Yang, D. Y.

    2017-12-01

    Sediment transfer within hill slope can be changed by the hydrologic characteristics of surface material on hill slope. To better understand sediment transfer of the past and future related to climate changes, studies for the changes of soil erosion due to hydrological characteristics changes by surface materials on hill slope are needed. To do so, on-situ rainfall simulating test was conducted on three different surface conditions, i.e. well covered with litter layer condition (a), undisturbed bare condition (b), and disturbed bare condition (c) and these results from rainfall simulating test were compared with that estimated using the Limburg Soil Erosion Model (LISEM). The result from the rainfall simulating tests showed differences in the infiltration rate (a > b > c) and the highest soil erosion rate was occurred on c condition. The result from model also was similar to those from rainfall simulating tests, however, the difference from the value of soil erosion rate between two results was quite large on b and c conditions. These results implied that the difference of surface conditions could change the surface runoff and soil erosion and the result from the erosion model might significantly underestimate on bare surface conditions rather than that from rainfall simulating test.

  16. Ceramic tantalum oxide thin film coating to enhance the corrosion and wear characteristics of Ti−6Al−4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Rahmati, B., E-mail: r.bijan@yahoo.com [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Sarhan, Ahmed A.D., E-mail: ah_sarhan@um.edu.my [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Basirun, W. Jeffrey [Department of Chemistry, University of Malaya, 50603 Kuala Lumpur (Malaysia); Abas, W.A.B.W. [Department of Biomedical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-08-15

    In this research, an attempt is made to study the corrosion and wear behavior of TaO{sub 2} thin film coating deposited onto Ti−6Al−4V alloy with the highest adhesion (was achieved in the author's previous experiments using Taguchi statistical method) which leads to increase corrosion resistance, decrease debris generation and improve durability. Accordingly, pure tantalum (Ta) was deposited onto Ti−6Al−4V substrate surface as intermetallic layer then to form a TaO{sub 2} thin film, Ta was deposited onto the sample surface in the presence of oxygen by using physical vapor deposition magnetron sputtering (PVDMS). Corrosion testing was carried out in fetal bovine serum (FBS). The corrosion test in FBS medium confirmed that the corrosion resistance of the TaO{sub 2} – coated Ti−6Al−4V alloys was significantly higher than the uncoated Ti−6Al−4V substrate due to the decrease in corrosion current density (I{sub corr}) for the coated substrate with high thin-film adhesion. Wear testing was carried out on uncoated and coated Ti−6Al−4V substrates in the presence of FBS medium under 15 N load (natural walking load) at 1.09 m/s (simulated medium walking speed). The tests revealed that the specific wear ratio of TaO{sub 2} coating was significantly lower than the uncoated substrate wear ratio. The average friction coefficients obtained were 0.183 and 0.152 for uncoated substrate and TaO{sub 2} thin film coating, respectively. So, due to the noticeable corrosion and wear resistance characteristics of the TaO{sub 2} coating, it is suggested for hip joint implant. - Highlights: • The TaO{sub 2} coating has been created onto the Ti−6Al−4V surface by using PVDMS method. • The TaO{sub 2} coating has been formed on the Ti−6Al−4V sample at the highest adhesion. • The corrosion resistance of the coated Ti−6Al−4V substrate has been improved. • The wear resistance of the coated Ti−6Al−4V substrate has been increased. • The durability

  17. Solid-fluid characteristics at the blast furnace hearth according to the nodal wear model (NWM)

    International Nuclear Information System (INIS)

    Martin, R.; Barbes, M. A.; Barbes, M. F.; Marinas, E.; Ayala, N.; Mochon, J.; Verdeja, L. F.; Garcia, F.

    2009-01-01

    The coke porosity is one of the most important variables that can affect the pig iron production and the lining corrosion. Up to now, the existing bibliography about lining corrosion always connects a deeper wear to an increase in the fluid flow (pig iron) at the blast furnace hearth. However, there is no evidence of any deterministic model that could link, from the theoretical point of view, the following variables: lining corrosion, porosity of dead coke and flow of pig iron at the hearth. Besides justifying the lining corrosion profiles, the Nodal Wear Model (NWM) can be an effective instrument to interpret the coke porosity and the pig iron speed rates that are generated inside the hearth. (Author) 23 refs

  18. Influence on grip of knife handle surface characteristics and wearing protective gloves.

    Science.gov (United States)

    Claudon, Laurent

    2006-11-01

    Ten subjects were asked to apply maximum torques on knife handles with either their bare hand or their hand wearing a Kevlar fibre protective glove. Four knife handles (2 roughnesses, 2 hardnesses) were tested. Surface electromyograms of 6 upper limb and shoulder muscles were recorded and subject opinions on both knife handle hardness and friction in the hand were also assessed. The results revealed the significant influence of wearing gloves (pgloves greatly increased the torque independently of the other two parameters. Under the bare hand condition, a 90 degrees ShA slightly rough handle provided the greatest torque. Subject opinion agreed with the observed effects on recorded torque values except for the hardness factor, for which a preference for the 70 degrees ShA value over the 90 degrees ShA value emerged.

  19. Friction and wear characteristics of Al-Cu/C composites synthesized using partial liquid phase casting process

    International Nuclear Information System (INIS)

    Ng, W.B.; Gupta, M.; Lim, S.C.

    1997-01-01

    During the sliding of aluminium alloys dispersed with graphite particulates, a layer of graphite is usually present at the sliding interface. This tribo-layer significantly reduces the amount of direct metal-to-metal contact, giving rise to low friction and a low rate of wear, making these composites useful candidate materials for anti-friction applications. Such self-lubricating composites are commonly fabricated via the squeeze casting, slurry casting or powder metallurgy route. These processes are expensive while the less-expensive conventional casting route is limited by the agglomeration of graphite particles in the composites, giving rise to poor mechanical properties. In this work, graphite particulate-reinforced Al-4.5 wt.% Cu composites with two effective graphite contents (Al-4.5 Cu/4.2 wt.% C and Al-4.5 Cu/6.8 wt.% C) were synthesized through an innovative partial liquid phase casting (rheocasting) technique, which is a modification of the conventional casting process. Unlubricated (without the use of conventional liquid lubrication) friction and wear performance of these composites as well as the un-reinforced aluminium alloy was determined using a pin-on-disk tester. The results revealed that the graphite-reinforced composites have a higher wear rate than the un-reinforced matrix alloy while their frictional characteristics are very similar within the range of testing conditions. Combining these with the information gathered from worn-surface examinations and wear-debris analysis, it is suggested that there exists a certain threshold for the amount and size of graphite particulates in these composites to enable them to have improved tribological properties. (Copyright (c) 1997 Elsevier Science B.V., Amsterdam. All rights reserved.)

  20. Stress concentration factor and stress intensity factor on hard metals in connection with the wear characteristics

    International Nuclear Information System (INIS)

    Dawihl, W.; Altmeyer, G.

    1977-01-01

    Description of a method to determine stress intensity factors on hard metals by lapping in notches of different diameter. Dependence of the values of the stress intensity factors on the size of the notch base diameter. For tungsten carbide hard metals with 6% Co, determination of a final value of 250 Nmm -3 / 2 . Characterisation of the stress intensity factor governed by the surface roughness which is decisive for the assessment of the wear-resistant behaviour. (orig.) [de

  1. Study on Friction and Wear Characteristics of Aluminum Alloy Hydraulic Valve Body and Its Antiwear Mechanism

    Directory of Open Access Journals (Sweden)

    Rong Li

    2017-03-01

    Full Text Available In order for the working status of the aluminum alloyed hydraulic valve body to be controlled in actual conditions, a new friction and wear design device was designed for the cast iron and aluminum alloyed valve bodies comparison under the same conditions. The results displayed that: (1 The oil leakage of the aluminum alloyed hydraulic valve body was higher than the corresponding oil leakage of the iron body during the initial running stage. Besides during a later running stage, the oil leakage of the aluminum alloyed body was lower than corresponding oil leakage of the iron body; (2 The actual oil leakage of different materials consisted of two parts: the foundation leakage that was the leakage of the valve without wear and wear leakage that was caused by the worn valve body; (3 The aluminum alloyed valve could rely on the dust filling furrow and melting mechanism that led the body surface to retain dynamic balance, resulting in the valve leakage preservation at a low level. The aluminum alloy modified valve body can meet the requirements of hydraulic leakage under pressure, possibly constituting this alloy suitable for hydraulic valve body manufacturing.

  2. Wear and Friction Characteristics of AlN/Diamond-Like Carbon Hybrid Coatings on Aluminum Alloy

    Science.gov (United States)

    Nakamura, Masashi; Kubota, Sadayuki; Suzuki, Hideto; Haraguchi, Tadao

    2015-10-01

    The use of diamond-like carbon (DLC) coatings has the potential to greatly improve the wear resistance and friction of aluminum alloys, but practical application has so far been limited by poor adhesion due to large difference in hardness and elasticity between the two materials. This study investigates the deposition of DLC onto an Al-alloy using an intermediate AlN layer with a graded hardness to create a hybrid coating. By controlling the hardness of the AlN film, it was found that the wear life of the DLC film could be improved 80-fold compared to a DLC film deposited directly onto Al-alloy. Furthermore, it was demonstrated through finite element simulation that creating a hardness gradient in the AlN intermediate layer reduces the distribution of stress in the DLC film, while also increasing the force of adhesion between the DLC and AlN layers. Given that both the DLC and AlN films were deposited using the same unbalanced magnetron sputtering method, this process is considered to represent a simple and effective means of improving the wear resistance of Al-alloy components commonly used within the aerospace and automotive industries.

  3. The impact of process variables and wear characteristics on the cutting tool performance using Finite Element Analysis

    OpenAIRE

    Jiang, Xiaoheng

    2016-01-01

    The frequent failure of cutting tool in the cutting process may cause a huge loss of money and time especially for hard to machine materials such as titanium alloys. Thus this study is mainly focused on the impact of wear characteristics and process variables on the cutting tool which is ignored by most of researchers. A thermo-mechanical finite element model of orthogonal metal cutting with segment chip formation is presented. This model can be used to predict the process performance in the ...

  4. Study on the characteristics of the impingement erosion-corrosion for Cu-Ni Alloy sprayed coating(I)

    International Nuclear Information System (INIS)

    Lee, Sang Yeol; Lim, Uh Joh; Yun, Byoung Du

    1998-01-01

    Impingement erosion-corrosion test and electrochemical corrosion test in tap water(5000Ω-cm) and seawater(25Ω-cm). Thermal spraying coated Cu-Ni alloy on the carbon steel was carried out. The impingement erosion-corrosion behavior and electrochemical corrosion characteristics of the substrate(SS41) and Cu-Ni thermal spray coating were investigated. The erosion-corrosion control efficiency of Cu-Ni coating to substrate was also estimated quantitatively. Main results obtained are as follows : 1) Under the flow velocity of 13m/s, impingement erosion-corrosion of Cu-Ni coating is under the control of electrochemical corrosion factor rather than that of mechanical erosion. 2) The corrosion potential of Cu-Ni coating becomes more noble than that of substrate, and the current density of Cu-Ni coating under the corrosion potential is drained lowly than that of substrate. 3) The erosion-corrosion control efficiency of Cu-Ni coating to substrate is excellent in the tap water of high specific resistance solution, but it becomes dull in the seawater of low specific resistance. 4) The corrosion control efficiency of Cu-Ni coating to substrate in the seawater appears to be higher than that in the tap water

  5. Soft drink, software and softening of teeth: a case report of tooth wear in the mixed dentition due to a combination of dental erosion and attrition

    NARCIS (Netherlands)

    Gambon, D.L.; Brand, H.S.; Nieuw Amerongen, A.V.

    2010-01-01

    This case report describes a 9-year-old boy with severe tooth wear as a result of drinking a single glass of soft drink per day. This soft drink was consumed over a period of one to two hours, while he was gaming intensively on his computer. As a result, a deep bite, enamel cupping, sensitivity of

  6. Optimization of performance, emission, friction and wear characteristics of palm and Calophyllum inophyllum biodiesel blends

    International Nuclear Information System (INIS)

    Mosarof, M.H.; Kalam, M.A.; Masjuki, H.H.; Alabdulkarem, Abdullah; Ashraful, A.M.; Arslan, A.; Rashedul, H.K.; Monirul, I.M.

    2016-01-01

    Highlights: • All of biodiesel blends were given higher BSFC than diesel fuel, except for CIB10. • Diesel produces higher BP and BTE as compared to PB and CIB blends. • CO and HC emissions of PB blends were reduced more than diesel and CIB blends. • PB blends contained lower metal compositions compared to diesel and CIB blends. • PB20 showed lower worn scar surfaces area compared to diesel and biodiesel blends. - Abstract: A running automobile engine produces more friction and wear between its sliding components than an idle one, and thus requires lubrication to reduce this frictional effect. Biodiesel is an alternative diesel fuel that is produced from renewable resources. Energy studies conducted over the last two decades focused on solutions to problems of rising fossil fuel price, increasing dependency on foreign energy sources, and worsening environmental concerns. Palm oil biodiesel is mostly used in Malaysia. This study conducted engine performance and emission tests with a single-cylinder diesel engine fueled with palm and Calophyllum inophyllum biodiesel blends (PB10, PB20, PB30, CIB10, CIB20, and CIB30) at a full-load engine speed range of 1000–2400 rpm, and then compared the results with those of diesel fuel. Friction and wear tests were conducted using the four-ball tester with different temperatures at 40 and 80 kg load conditions and a constant speed of 1800 rpm. The average brake specific fuel consumption increased from 7.96% to 10.15% while operating on 10%, 20%, and 30% blends of palm and C. inophyllum biodiesel. The respective average brake powers for PB20 and PB30 were 9.31% and 12.93% lower compared with that for diesel fuel. PB20 produced relatively lower CO and HC emissions than the diesel and biodiesel blends. Diesel produced low amounts of NO_X emission, and the CIB blend produced a lower frictional coefficient compared with the diesel and PB blends. PB30 showed high average FTP and low average WSD, both of which enhanced

  7. Estimation of erosion amount by geochemical characteristic in the Horonobe area, northern Hokkaido

    International Nuclear Information System (INIS)

    Takahashi, Kazuharu; Niizato, Tadafumi; Yasue, Ken-ichi; Ishii, Eiichi

    2005-08-01

    This article presents the results of the estimated amount of erosion and uplifting based on mineralogy and organic geochemical characters of the Neogene siliceous rock (Wakkanai and Koetoi Formations) in Horonobe. As a result of the transformational change of silica minerals, it was clarified that the erosion amount was about 0.66 [m ky -1 ] or more at the large uplift site, and about 0.21 [m ky -1 ] or more at the small uplift site at Hokushin region, Horonobe area. In this case of the correlation with the palaeo-geothermal temperature and the sterane/sterene ratio, the ratio is effective measure to estimate the burial depth and erosion amount. We think that the estimation of the amount of erosion and uplifting became possible in high resolution by the organic geochemical character. (author)

  8. Root characteristics of cover crops and their erosion-reducing potential during concentrated runoff

    Science.gov (United States)

    de Baets, S.; Poesen, J.

    2009-04-01

    In the loam region in central Belgium, a lot of research has been conducted on the effects of cover crops for preventing splash and interrill erosion and on their nutrient pumping effectiveness. As this is a very effective erosion and environment conservation technique, planting cover crops during the winter season is widely applied in the loess belt. Most of these cover crops freeze at the beginning of the winter period. Consequently, the above-ground biomass becomes less effective in protecting the soil from water erosion. Apart from the effects of the above-ground biomass in protecting the soil against raindrop impacts and reducing flow velocities by the retarding effects of their stems, plant roots also play an important role in improving soil strength. Previous research showed that roots contribute to a large extent to the resistance of topsoils against concentrated flow erosion. Unfortunately, information on root properties of common cover crops (e.g. Sinapis alba, Phacelia tanacetifoli, Lolium perenne, Avena sativa, Secale cereale, Raphanus sativus subsp. oleiferus) is very scarce. Therefore, root density distribution with depth and their erosion-reducing effects during concentrated flow erosion were assessed by conducting root auger measurements and concentrated flow experiments at the end of the growth period (December). The preliminary results indicate that the studied cover crops are not equally effective in preventing soil loss by concentrated flow erosion at the end of the growing season. Cover crops with thick roots, such as Sinapis alba and Raphanus sativus subsp. oleiferus are less effective than cover crops with fine-branched roots such as Phacelia tanacetifoli, Lolium perenne (Ryegrass), Avena sativa (Oats) and Secale cereale (Rye) in preventing soil losses by concentrated flow erosion. These results enable soil managers to select the most suitable crops and maximize soil protection.

  9. Wear and microstructural characteristics of spray atomized zircon sand reinforced LM13 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, K.; Pandey, O.P. [School of Physics and Materials Science, Thapar University Patiala, Punjab (India)

    2010-07-15

    The requirement of the high performance light weight materials demands the development of varieties of materials within the economical range to get it commercialized. Light weight aluminium alloys are used in several structural applications like automotive, aerospace, defense industry and other fields of engineering. The ceramic particle reinforced aluminium metal matrix composites (AMCs) have emerged as a suitable candidate for commercial applications. A variety of processing routes have been adopted to manufacture AMCs. In the present work LM13 alloy reinforced with zircon sand is formed via spray forming. During experimentation a self prepared convergent-divergent nozzle is used for inert gas atomization of the melt which is subsequently deposited on copper substrate placed vertically below the atomizer. The zircon sand particles are injected in the atomization zone by external injectors aligned perpendicular to the gas atomization axis. Zircon sand has been found to have new promising economical commercial candidate due to its easy availability and good mechanical properties like high hardness, high modulus of elasticity and good thermal stability. The microhardness of cast alloy and spray formed composite shows that the spray formed zircon sand reinforced composite has higher hardness. Also the lower wear rate has been observed in case of the zircon sand reinforced AMC as compared to LM13 alloy. This behaviour is further analyzed in light of microstructural features of the spray deposited composite using optical and scanning electron microscope (SEM). A comparative study of this material (LM13/Zircon sand) with the parent alloy (LM13) is presented in this work. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  10. Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

    Directory of Open Access Journals (Sweden)

    Qian Feng

    2016-09-01

    Full Text Available Hydrological processes play important roles in soil erosion processes of the hillslopes. This study was conducted to investigate the hydrological processes and the associated erosional responses on the purple soil slope. Based on a comprehensive survey of the Wangjiaqiao watershed in the Three Gorges Reservoir, four typical slope gradients (5°, 10°, 15°and 20° were applied to five rainfall intensities (0.6, 1.1, 1.61, 2.12 and 2.54 mm·min-1. The results showed that both surface and subsurface runoff varied greatly depending on the rainfall intensity and slope gradient. Surface runoff volume was 48.1 to 280.1 times of that for subsurface runoff. The critical slope gradient was about 10°. The sediment yield rate increased with increases in both rainfall intensity and slope gradient, while the effect of rainfall intensity on the sediment yield rate was greater than slope gradient. There was a good linear relationship between sediment yield rate and Reynolds numbers, flow velocity and stream power, while Froude numbers, Darcy-Weisbach and Manning friction coefficients were not good hydraulic indicators of the sediment yield rate of purple soil erosion. Among the three good indicators (Re, v and w, stream power was the best predictor of sediment yield rate (R2 = 0.884. Finally, based on the power regression relationship between sediment yield rate, runoff rate, slope gradient and rainfall intensity, an erosion model was proposed to predict the purple soil erosion (R2 = 0.897. The results can help us to understand the relationship between flow hydraulics and sediment generation of slope erosion and offer useful data for the building of erosion model in purple soil.

  11. Heat transfer, erosion and acid condensation characteristics for novel H-type finned oval tube

    International Nuclear Information System (INIS)

    Wang, Y; Zhao, X; Tang, G

    2015-01-01

    Low efficiency of heat transfer, acid corrosion and erosion of economizers affect the economy and security in coal-fired power plants significantly. The H-type finned oval tube is proposed to alleviate these problems. Based on the H-type finned oval tube, we investigated three novel types of fins, including bleeding dimples, longitudinal vortex generators (LVGs), and compound dimple-LVG. We considered the three aspects together, and obtained the heat transfer, acid condensation rate and erosion loss. The results show that the tube bank with the new structured fins can improve the performance on the three aspects, and the compound dimple-LVG performs the highest comprehensive effect. (paper)

  12. Pathogenic characteristics of Candida albicans isolated from oral cavities of denture wearers and cancer patients wearing oral prostheses.

    Science.gov (United States)

    Mothibe, J V; Patel, M

    2017-09-01

    Candida albicans cause opportunistic infections including oral candidiasis in immunocompromised patients. It has an ability to cause infection due to its virulence factors. This study investigated the pathogenic characteristics of C. albicans isolated from the oral cavities of healthy subjects and two vulnerable groups, denture wearers and cancer patients wearing oral prostheses. Oral rinse samples were collected and cultured for the quantitative and qualitative analysis of Candida. Twenty strains of C. albicans isolated from the healthy individuals and denture wearers and, 14 strains isolated from the cancer patients were selected and their pathogenic characteristics were measured. The results of the study groups were compared using a Scheffe test for pairwise comparison and a chi square test. Denture wearer and cancer patients with prostheses carried significantly higher number (p production were significantly higher in the strains from denture wearers. In addition, high number of isolates from the denture wearers produced phospholipase and proteinase (85% and 80% respectively) compared to the strains from normal subjects (25% and 60% respectively). Only the germ tube formation and adherence ability were significantly higher in the strains from the cancer patients with prostheses (p = 0.05 and p oral cavity and prostheses is important in the prevention of colonization of Candida and the development of oral candidiasis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Characteristics of Soil and Organic Carbon Loss Induced by Water Erosion on the Loess Plateau in China.

    Science.gov (United States)

    Li, Zhongwu; Nie, Xiaodong; Chang, Xiaofeng; Liu, Lin; Sun, Liying

    2016-01-01

    Soil erosion has been a common environmental problem in the Loess Plateau in China. This study aims to better understand the losses of soil organic carbon (SOC) induced by water erosion. Laboratory-simulated rainfall experiments were conducted to investigate the characteristics of SOC loss induced by water erosion. The applied treatments included two rainfall intensities (90 and 120 mm h-1), four slope gradients (10°, 15°, 20°, and 25°), and two typical soil types- silty clay loam and silty loam. Results showed that the sediment OC enrichment ratios (ERoc) in all the events were relative stable with values ranged from 0.85 to1.21 and 0.64 to 1.52 and mean values of 0.98 and 1.01 for silty clay loam and silty loam, respectively. Similar to the ERoc, the proportions of different sized particles in sediment showed tiny variations during erosion processes. No significant correlation was observed between ERoc values and the proportions of sediment particles. Slope, rainfall intensity and soil type almost had no impact on ERoc. These results indicate that the transportation of SOC during erosion processes was nonselective. While the mean SOC loss rates for the events of silty clay loam and silty loam were 0.30 and 0.08 g m-2 min-1, respectively. Greater differences in SOC loss rates were found in events among different soil types. Meanwhile, significant correlations between SOC loss and soil loss for all the events were observed. These results indicated that the amount of SOC loss was influenced primarily by soil loss and the SOC content of the original soil. Erosion pattern and original SOC content are two main factors by which different soils can influence SOC loss. It seems that soil type has a greater impact on SOC loss than rainfall characteristics on the Loess Plateau of China. However, more kinds of soils should be further studied due to the special formation processes in the Loess Plateau.

  14. Multivariate Analysis of Erosivity Indices and Rainfall Physical Characteristics Associated with Rainfall Patterns in Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Roriz Luciano Machado

    2017-12-01

    Full Text Available ABSTRACT The identification of areas with greater erosive potential is important for planning soil and water conservation. The objective of this study was to evaluate the physical characteristics of rainfall events in the state of Rio de Janeiro, Brazil, and their interactions with rainfall patterns through multivariate statistical analysis. Rainfall depth, kinetic energy, 30-min intensity (I30, duration of rainfall events, and the erosivity indices KE >10, KE >25, and EI30 in 36 locations (stations were subjected to principal component analysis (PCA and canonical discriminant analysis (CDA. Based on evaluation of the respective historical series of hyetographs, it was found that the advanced pattern occurs with highest frequency (51.8 %, followed by the delayed pattern (26.1 %, and by the intermediate pattern (22.1 %. All the evaluated rainfall characteristics have high response capacity in describing localities and rainfall patterns through PCA and CDA. In CDA, the Tukey test (p<0.05 applied to the scores of the first canonical discriminant function (CDF1 allowed differentiation of the stations with respect to the rainfall and erosivity characteristics for the advanced and delayed patterns. In the delayed pattern, the localities of Angra dos Reis, Campos, Eletrobrás, Manuel Duarte, Santa Isabel do Rio Preto, Tanguá, Teresópolis, Vila Mambucaba, and Xerém had the highest CDF1 scores, indicating that they have rainfalls with higher depth, I30, and duration because the standardized canonical coefficient (SCC and the correlation coefficient (“r” of these characteristics were positive. The rainfall events in the state of Rio de Janeiro differ from one locality to another in relation to the advanced and delayed rainfall patterns, mainly due to the physical characteristics of rainfall depth, I30, and duration, indicating a higher risk of soil loss and runoff in the localities where rainfall events with the delayed pattern prevail.

  15. Trends in characteristics of sub-daily heavy precipitation and rainfall erosivity in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Hanel, M.; Pavlásková, A.; Kyselý, Jan

    2016-01-01

    Roč. 36, č. 4 (2016), s. 1833-1845 ISSN 0899-8418 Institutional support: RVO:67179843 Keywords : sub-daily precipitation * fainfall events * erosivity * extremes * climate variability * Central Europe Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.760, year: 2016

  16. Characteristics and distribution of soil piping erosion in loess-derived soils of Belgium

    International Nuclear Information System (INIS)

    Verachtert, E.; Van Den Eeckhaut, M.; Poesen, J.; Deckers, J.

    2009-01-01

    Subsurface erosion (piping, tunnel erosion) in non-karstic landscapes has been considered of little importance compared to sheet and gully erosion for a long time. Although the basic factors responsible for piping in certain environments are well understood, there is still uncertainty about the topographic and soil properties inducing subsurface pipe development in loess-derived soils under temperate climate. Therefore, this research aims at understanding the factors controlling the occurrence of piping erosion in the loess-derived soils of the Flemish Ardennes (Belgium). Analysis of ortho photos as well as field surveys were conducted to detect the sites with piping in the study area. Enquiries among farmers and technical services were carried out. In total, 114 sites (parcels) with 301 collapsed soil pipes were found in a 170 kM 2 study area. For each site with piping, data was collected on possible controlling factors: topographic parameters, land use, lithology and soil type. Land use plays an important role as 94% of the sites with piping are found under pasture. (Author) 15 refs.

  17. Characteristics and distribution of soil piping erosion in loess-derived soils of Belgium

    Energy Technology Data Exchange (ETDEWEB)

    Verachtert, E.; Van Den Eeckhaut, M.; Poesen, J.; Deckers, J.

    2009-07-01

    Subsurface erosion (piping, tunnel erosion) in non-karstic landscapes has been considered of little importance compared to sheet and gully erosion for a long time. Although the basic factors responsible for piping in certain environments are well understood, there is still uncertainty about the topographic and soil properties inducing subsurface pipe development in loess-derived soils under temperate climate. Therefore, this research aims at understanding the factors controlling the occurrence of piping erosion in the loess-derived soils of the Flemish Ardennes (Belgium). Analysis of ortho photos as well as field surveys were conducted to detect the sites with piping in the study area. Enquiries among farmers and technical services were carried out. In total, 114 sites (parcels) with 301 collapsed soil pipes were found in a 170 kM{sup 2} study area. For each site with piping, data was collected on possible controlling factors: topographic parameters, land use, lithology and soil type. Land use plays an important role as 94% of the sites with piping are found under pasture. (Author) 15 refs.

  18. Wear Micro-Mechanisms of Composite WC-Co/Cr - NiCrFeBSiC Coatings. Part II: Cavitation Erosion

    Directory of Open Access Journals (Sweden)

    D. Kekes

    2014-12-01

    Full Text Available Composite coatings with five different proportions of WC-Co/Cr and NiCrFeBSiC components were deposited on stainless steel by HVOF spraying. Cavitation erosion tests were performed and the material removal micro-mechanisms were identified by SEM of both the eroded areas and the specimens’ cross-sections. Waves’ propagation and deflection at the weak interfaces within the coatings resulted in local tensile stresses perpendicular to the interface direction that eventually led to material removal. Such weak interfaces are the boundaries of the carbide particles with the metal binder within the same splat, those between splats along the same layer and those between successively deposited layers.

  19. The Wear Characteristics of Heat Treated Manganese Phosphate Coating Applied to AlSi D2 Steel with Oil Lubricant

    Directory of Open Access Journals (Sweden)

    Venkatesan Alankaram

    2012-12-01

    Full Text Available Today, in the area of material design conversion coatings play an important role in the applications where temperature, corrosion, oxidation and wear come in to play. Wear of metals occurs when relative motion between counter-surfaces takes place, leading to physical or chemical destruction of the original top layers. In this study, the tribological behaviour of heat treated Manganese phosphate coatings on AISI D2 steel with oil lubricant was investigated. The Surface morphology of manganese phosphate coatings was examined by Scanning Electron Microscope (SEM and Energy Dispersive X-ray Spectroscopy (EDX .The wear tests were performed in a pin on disk apparatus as per ASTM G-99 Standard. The wear resistance of the coated steel was evaluated through pin on disc test using a sliding velocity of 3.0m/s under Constant loads of 40 N and 100 N with in controlled condition of temperature and humidity. The Coefficient of friction and wear rate were evaluated. Wear pattern of Manganese phosphate coated pins with oil lubricant, Heat treated Manganese phosphate coated pins with oil lubricant were captured using Scanning Electron Microscope (SEM. The results of the wear test established that the heat treated manganese phosphate coating with oil lubricant exhibited the lowest average coefficient of friction and the lowest wear loss up to 6583 m sliding distance under 40 N load and 3000 m sliding distance even under 100 N load respectively. The Wear volume and temperature rise in heat treated Manganese Phosphate coated pins with oil lubricant is lesser than the Manganese Phosphate coated pins with oil lubricant

  20. Vegetation morphologic and aerodynamic characteristics reduce aeolian erosion.

    Science.gov (United States)

    Miri, Abbas; Dragovich, Deirdre; Dong, Zhibao

    2017-10-09

    Vegetation cover is crucial to controlling aeolian erosion but highly efficient vegetation is critical. How this efficiency is influenced by vegetation response to airflow is not clear. Here we evaluate the responses of Cosmos bipinnatus and Ligustrum lucidum Ait to a range of wind speeds in a wind tunnel. For both species, we calculate shelter effect and sand flux. We show that plant effectiveness in reducing wind speed and sediment transport is linked to their aerodynamic response to airflow which results from their morphology. We demonstrate that in low-density cover the flow-response and resistance of individuals is most critical in the optimal effectiveness of a canopy. Our wind tunnel experiment suggests that vegetation morphology and structure must be priority parameters in facilitating aeolian erosion control.

  1. Swelling, erosion and drug release characteristics of salbutamol sulfate from hydroxypropyl methylcellulose-based matrix tablets.

    Science.gov (United States)

    Chaibva, Faith A; Khamanga, Sandile M M; Walker, Roderick B

    2010-12-01

    Hydrophilic matrix formulations are important and simple technologies that are used to manufacture sustained release dosage forms. Hydroxypropyl methylcellulose-based matrix tablets, with and without additives, were manufactured to investigate the rate of hydration, rate of erosion, and rate and mechanism of drug release. Scanning electron microscopy was used to assess changes in the microstructure of the tablets during drug release testing and whether these changes could be related to the rate of drug release from the formulations. The results revealed that the rate of hydration and erosion was dependent on the polymer combination(s) used, which in turn affected the rate and mechanism of drug release from these formulations. It was also apparent that changes in the microstructure of matrix tablets could be related to the different rates of drug release that were observed from the test formulations. The use of scanning electron microscopy provides useful information to further understand drug release mechanisms from matrix tablets.

  2. Trends in characteristics of sub-daily heavy precipitation and rainfall erosivity in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Hanel, M.; Pavlásková, A.; Kyselý, Jan

    2016-01-01

    Roč. 36, č. 4 (2016), s. 1833-1845 ISSN 0899-8418 R&D Projects: GA ČR(CZ) GA14-18675S Institutional support: RVO:68378289 Keywords : sub-daily precipitation * rainfall events * erosivity * extremes * climate variability * Central Europe Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.760, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/joc.4463/abstract

  3. Runoff erosion

    OpenAIRE

    Evelpidou, Niki (Ed.); Cordier, Stephane (Ed.); Merino, Agustin (Ed.); Figueiredo, Tomás de (Ed.); Centeri, Csaba (Ed.)

    2013-01-01

    Table of Contents PART I – THEORY OF RUNOFF EROSION CHAPTER 1 - RUNOFF EROSION – THE MECHANISMS CHAPTER 2 - LARGE SCALE APPROACHES OF RUNOFF EROSION CHAPTER 3 - MEASURING PRESENT RUNOFF EROSION CHAPTER 4 - MODELLING RUNOFF EROSION CHAPTER 5 - RUNOFF EROSION AND HUMAN SOCIETIES: THE INFLUENCE OF LAND USE AND MANAGEMENT PRACTICES ON SOIL EROSION PART II - CASE STUDIES CASE STUDIES – INTRODUCTION: RUNOFF EROSION IN MEDITERRANEAN AREA CASE STUDY 1: Soil Erosion Risk...

  4. Theoretical model for cavitation erosion prediction in centrifugal pump impeller

    International Nuclear Information System (INIS)

    Rayan, M.A.; Mahgob, M.M.; Mostafa, N.H.

    1990-01-01

    Cavitation is known to have great effects on pump hydraulic and mechanical characteristics. These effects are mainly described by deviation in pump performance, increasing vibration and noise level as well as erosion of blade and casing materials. In the present work, only the hydrodynamic aspect of cavitation was considered. The efforts were directed toward the study of cavitation inception, cavity mechanics and material erosion in order to clarify the macrohydrodynamic aspects of cavitation erosive wear in real machines. As a result of this study, it was found that cavitation damage can be predicted from model data. The obtained theoretical results show good agreement with the experimental results obtained in this investigation and with results of some other investigations. The application of the findings of this work will help the design engineer in predicting the erosion rate, according to the different operating conditions. (author)

  5. Microstructural characteristics, mechanical and wear behaviour of aluminium matrix hybrid composites reinforced with alumina, rice husk ash and graphite

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayo Alaneme

    2015-09-01

    Full Text Available The microstructural characteristics, mechanical and wear behaviour of Aluminium matrix hybrid composites reinforced with alumina, rice husk ash (RHA and graphite were investigated. Alumina, RHA and graphite mixed in varied weight ratios were utilized to prepare 10 wt% hybrid reinforced Al-Mg-Si alloy based composites using two-step stir casting. Hardness, tensile properties, scanning electron microscopy, and wear tests were used to characterize the composites produced. The results show that Hardness decreases with increase in the weight ratio of RHA and graphite in the composites; and with RHA content greater than 50%, the effect of graphite on the hardness becomes less significant. The tensile strength for the composites containing o.5wt% graphite and up to 50% RHA was observed to be higher than that of the composites without graphite. The toughness values for the composites containing 0.5wt% graphite were in all cases higher than that of the composites without graphite. The % Elongation for all composites produced was within the range of 10–13% and the values were invariant to the RHA and graphite content. The tensile fracture surface morphology in all the composites produced was identical characterized with the presence of reinforcing particles housed in ductile dimples. The composites without graphite exhibited greater wear susceptibility in comparison to the composite grades containing graphite. However the wear resistance decreased with increase in the graphite content from 0.5 to 1.5 wt%.

  6. Mechanical Properties and Wear Characteristics Al-ZrO2-SiCp and Graphite Hybrid Metal Matrix Composites

    Science.gov (United States)

    Nayak, S. K.; Mahanta, T.; Sahoo, J. K.; Mishra, A.

    2018-03-01

    Development of Aluminum Metal Matrix Co mposites (AMMCs) has been one of the major requirements in engineering applicat ions due to their excellent mechanical properties, light weight and high strength. In the present investigation, Stir casting technique has been used for fabrication of co mposites, taking Alu miniu m as parent metal, Silicon Carbide (SiCp) of 7 vol. % of 220 mesh size and 1.75 vol. % of graphite as reinforcements. The Zirconia content was varied as 2.75, 4.5 and 6 vol. % to fabricate three d ifferent types of hybrid composites. The tensile strength and hardness were measured in UTM and Vickers hardness tester respectively and the wear characteristics were studied in a pin on disc friction monitor under dry sliding condition against steel counter face. The tensile strength was found to be 90 MPa, 120 MPa, 130 MPa and hardness 80.25 VHN, 103.22 VHN, 103.77 VHN for 2.75, 4.5 and 6vol. % of Zirconia respectively. Fro m the above investigation, it is recommended that composition with Al, 7 %-SiCp, 1.75 % -Gr and 6 vol %-ZrO2 showed better mechanical p roperties i.e . h igh tensile strength (130MPa) and reasonably good hardness (103.77 VHN) . The co mposite with Al, 7 % - SiCp, 1.75 % -Gr and 6 %-ZrO2 is good for short run frictional applicat ion and the composite with Al, 7 %- SiCp, 1.75 % -Gr and 4.5 %- ZrO2 may be used for long run frictional applicat ions after testing.

  7. Fluisd elastic instability and fretting-wear characteristics of steam generator helical tubes subjected to single-phase external flow and two-phase internal flow

    International Nuclear Information System (INIS)

    Jo, Jong Chull; Jhung, Myung Jo; Kim, Woong Sik; Kim, Hho Jung

    2004-01-01

    This study investigates the fluid elastic instability characteristics of steam generator (SG) helical type tubes and the safety assessment of the potential for fretting-wear damages caused by foreign object in operating nuclear power plants. The thermal-hydraulic conditions of both tube side and shell side flow fields are predicted by a general purpose computational fluid dynamics code employing the finite volume element modeling. To get the natural frequency, corresponding mode shape and participation factor, modal analyses are performed for helical type tubes with various conditions. Special emphases are on the effects of coil diameter and the number of turns on the modal and instability characteristics of tubes, which are expressed in terms of the natural frequency, corresponding mode shape and stability ratio. Also, the wear rate of helical type tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted, and discussed in this study is the effect of the flow velocity and vibration of the tube on the remaining life of the tube. In addition, addressed is the effect of the external pressure on the vibration and fretting wear characteristics of the tube

  8. Effects of working gas pressure on zirconium dioxide thin film prepared by pulsed plasma deposition: roughness, wettability, friction and wear characteristics.

    Science.gov (United States)

    Berni, M; Marchiori, G; Gambardella, A; Boi, M; Bianchi, M; Russo, A; Visani, A; Marcacci, M; Pavan, P G; Lopomo, N F

    2017-08-01

    In joint arthroplasty one of the main issues related to the failure of prosthetic implants is due to the wear of the ultra-high molecular weight polyethylene (UHMWPE) component. Surface treatments and coatings have been recognized as enhancing methods, able to improve the tribological properties of the implants. Therefore, the main objective of this work was to investigate the possibility to fabricate yttria-stabilized zirconia (YSZ) coatings on a metal (AISI 316-L) substrate by means of Pulsed Electron Deposition, in order to improve the tribological behavior of the polymer-metal coupling, by reducing the initial wear of the UHMWPE component. In order to optimize the coating characteristics, the effects of working gas pressure on both its morphological and tribological properties were analyzed. Morphological characterization of the films was evaluated by Atomic Force Microscopy (AFM). Coating wettability was also estimated by contact angle (CA) measurement. Tribological performance (coupling friction and wear of UHMWPE) was evaluated by using a ball-on-disc tribometer during highly-stressing tests in dry and lubricated (i.e. NaCl and serum) conditions; friction and wear were specifically evaluated at the initial sliding distances - to highlight the main effect of coating morphology - and after 100m - where the influence of the intrinsic materials properties prevails. AFM analysis highlighted that the working pressure heavily affected the morphological characteristics of the realized films. The wettability of the coating at the highest and lowest deposition pressures (CA ~ 60°, closed to substrate value) decreased for intermediate pressures, reaching a maximum CA of ~ 90°. Regarding tribological tests, a strong correlation was found in the initial steps between friction coefficient and wettability, which decreased as the distance increased. Concerning UHMWPE wear associated to coated counterpart, at 100m a reduction rate of about 7% in dry, 12% in NaCl and 5% in

  9. Effect of Micro Electrical Discharge Machining Process Conditions on Tool Wear Characteristics: Results of an Analytic Study

    DEFF Research Database (Denmark)

    Puthumana, Govindan; P., Rajeev

    2016-01-01

    Micro electrical discharge machining is one of the established techniques to manufacture high aspect ratio features on electrically conductive materials. This paper presents the results and inferences of an analytical study for estimating theeffect of process conditions on tool electrode wear...... characteristicsin micro-EDM process. A new approach with two novel factors anticipated to directly control the material removal mechanism from the tool electrode are proposed; using discharge energyfactor (DEf) and dielectric flushing factor (DFf). The results showed that the correlation between the tool wear rate...... (TWR) and the factors is poor. Thus, individual effects of each factor on TWR are analyzed. The factors selected for the study of individual effects are pulse on-time, discharge peak current, gap voltage and gap flushing pressure. The tool wear rate decreases linearly with an increase in the pulse on...

  10. Assessment and management of dental erosion.

    Science.gov (United States)

    Wang, Xiaojie; Lussi, Adrian

    2010-07-01

    Studies have shown a growing trend toward increasing prevalence of dental erosion, associated with the declining prevalence of caries disease in industrialized countries. Erosion is an irreversible chemical process that results in tooth substance loss and leaves teeth susceptible to damage as a result of wear over the course of an individual's lifetime. Therefore, early diagnosis and adequate prevention are essential to minimize the risk of tooth erosion. Clinical appearance is the most important sign to be used to diagnose erosion. The Basic Erosive Wear Examination (BEWE) is a simple method to fulfill this task. The determination of a variety of risk and protective factors (patient-dependent and nutrition-dependent factors) as well as their interplay are necessary to initiate preventive measures tailored to the individual. When tooth loss caused by erosive wear reaches a certain level, oral rehabilitation becomes necessary. Copyright 2010 Elsevier Inc. All rights reserved.

  11. Prevalencia de erosión dental en niños de 6 a 12 años de edad utilizando el índice Basic Erosive Wear Examination (BEWE

    Directory of Open Access Journals (Sweden)

    Karla Rosella Baltuano Songhurst

    2016-01-01

    Full Text Available Objetivos: El objetivo de este estudio fue determinar la prevalencia, distribución y severidad de erosión dental en niños de 6 a 12 años de edad de la institución educativa pública Domingo Faustino Sarmiento, Lima-Perú. Material y métodos: Una muestra aleatoria de 247 niños de primaria fueron evaluados clínicamente para medir la erosión dental utilizando el índice Basic Erosive Wear Examination (BEWE, obteniendo un score acumulativo el cual posteriormente es comparado con el cuadro de niveles de riesgo/manejo clínico propio del índice. Se realizó un análisis descriptivo de las variables presencia de erosión dental, género, edad, localización de la lesión. Resultados: La prevalencia de erosión dental fue de 9.31% y la media y DS del score BEWE fue 0.25±0.90. Conclusiones: La erosión dental en niños de 6 a 12 años encontrada en esta institución educativa es menor a la de otros estudios epidemiológicos realizados en escuelas de otras partes del mundo. Este tipo de estudio epidemiológico puede ser viable en niños de este rango de edad de otras partes del Perú, en donde las costumbres, hábitos alimenticios y otros factores varían notablemente.

  12. [Comparison of in vivo characteristics of polyethylene wear particles produced by a metal and a ceramic femoral component in total knee replacement].

    Science.gov (United States)

    Veigl, D; Vavřík, P; Pokorný, D; Slouf, M; Pavlova, E; Landor, I

    2011-01-01

    The aim of the study was to evaluate in vivo and compare, in terms of the quality and number of ultra high-molecular polyethylene (UHMWPE) wear particles, total knee replacements of identical construction differing only in the material used for femoral component production, i.e., CoCrMo alloy or ZrO2 ceramics. Samples of peri-prosthetic granuloma tissue were collected in two patients with total knee replacement suffering from implant migration, who were matched in relevant characteristics. The primary knee replacement in Patient 1 with a CoCrMo femoral component was done 7.2 years and in Patient 2 with a ZrO2 implant 6.8 years before this assessment. The polyethylene wear-induced granuloma was analysed by the MORF method enabling us to assess the shape and size of wear debris and the IRc method for assessment of particle concentration. In the granuloma tissue samples of Patient 1, on the average, particles were 0.30 mm in size and their relative volume was 0.19. In the Patient 2 tissue samples, the average size of particles was 0.33 mm and their relative volume was 0.26. There was no significant difference in either particle morphology or their concentration in the granuloma tissue between the two patients. One of the options of how to reduce the production of polyethylene wear particles is to improve the tribological properties of contacting surfaces in total knee replacement by substituting a cobalt-chrome femoral component with a zirconia ceramic femoral component. The previous in vitro testing carried out with a mechanical simulator under conditions approaching real weight-bearing in the human body did show a nearly three-fold decrease in the number of UHMWPE wear particles in zirconia components. The evaluation of granuloma tissue induced by the activity of a real prosthetic joint for nearly seven years, however, did not reveal any great difference in either quality or quantity of polyethylene debris between the two replacements. The difference of surface

  13. Effects of a Nano-Silica Additive on the Rock Erosion Characteristics of a SC-CO2 Jet under Various Operating Conditions

    Directory of Open Access Journals (Sweden)

    Man Huang

    2017-02-01

    Full Text Available In order to improve the erosion capacity of a supercritical carbon dioxide (SC-CO2 jet, the influence of a nano-silica additive on the rock erosion characteristics was experimentally investigated. By impinging the SC-CO2 jets with nano-silica mass fractions of 0 wt % (pure SC-CO2 jet, 3 wt %, 6 wt %, 9 wt %, 12 wt %, 15 wt %, and 18 wt % on specimens of red sandstone, the erosion volumes under various operating conditions were measured and analyzed. Results show that an appropriate amount of nano-silica additive can greatly enhance the erosion ability of a SC-CO2 jet. The effect on the erosion ability largely depends on the operating conditions. For instance, when the other conditions are fixed, 6 wt %, 9 wt %, 12 wt %, and 15 wt % were the optimum mass fractions, successively, with the inlet pressure increasing from 30 MPa to 60 MPa. With the increase in ambient pressure, the optimum mass fraction is unchanged under the constant inlet pressure, while it increases under the constant pressure drop. Additionally, the optimum mass fraction decreases when the fluid temperature increases. In addition, the optimal standoff distances are about five times the nozzle diameter of the nano-silica SC-CO2 jet, and three times for the pure jet. This research provides a new method for effectively enhancing the rock erosion performance of a SC-CO2 jet.

  14. Compressor Impeller Erosion Resistant Surface Treatment

    National Research Council Canada - National Science Library

    Riley, Michael

    2000-01-01

    ...). Coatings based on tungsten carbide tantalum carbide. titanium carbide all with a cobalt matrix were evaluated for high velocity particle erosion in conventional wear test studies as well as wind tunnel testing...

  15. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S

    1981-01-01

    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  16. Microstructural evolution and wear characteristics of equal channel angular pressing processed semi-solid-cast hypoeutectic aluminum alloys

    International Nuclear Information System (INIS)

    Thuong, Nguyen Van; Zuhailawati, Hussain; Seman, Anasyida Abu; Huy, Tran Duc; Dhindaw, Brij Kumar

    2015-01-01

    Highlights: • We produced aluminum feedstock for ECAP by two casting techniques: conventional and with cooling slope. • Globular α-Al phase was found in cooling slope sample compared to dendritic in the conventional. • After ECAP uniform Si particles distribution and fine α-Al were observed for cooling slope. • We observed significant improvement in wear resistance of ECAPed sample produced by cooling slope. - Abstract: This work investigated the microstructural evolution of Al–7Si–Mg alloy cast semi-solid using a cooling slope as well as conventional casting followed by equal channel angular pressing (ECAP) in a 120° die. Feed materials were prepared for ECAP by cooling slope casting and by conventional casting. The microstructure of the processed alloys extruded was observed by optical microscope and by transmission electron microscope, and their hardness and wear resistance were evaluated. After ECAP processing, the primary α-Al phase tended to be elongated while the Si particles became fragmented and more nearly globular in shape and uniform in size than in the as-cast sample. The microstructure of the cooling slope-cast ECAPed samples was more homogenous than that of the conventionally cast ECAPed sample. The α-Al phase sub-grains were refined to sub-micrometer sizes for samples cast by both methods after ECAP. The hardness of the cooling slope-cast ECAPed sample was also higher than that of the conventionally cast ECAPed sample. The wear resistance of the alloy improved after cooling slope casting and ECAP processing

  17. Dental erosion among South Brazilian adolescents: A 2.5-year longitudinal study.

    Science.gov (United States)

    Brusius, C D; Alves, L S; Susin, C; Maltz, M

    2018-02-01

    This population-based longitudinal study investigated the incidence, progression and risk factors for dental erosion among South Brazilian adolescents. Eight hundred and one schoolchildren attending 42 public and private schools were clinically examined at 12 years of age; clinical examinations were repeated after 2.5 years (SD=0.3). After tooth cleaning and drying, permanent incisors and first molars were classified using the Basic Erosive Wear Examination (BEWE) scoring criteria. Questionnaires were used to collect data on socio-demographic characteristics, dietary habits, toothbrushing frequency and general health. Poisson regression analysis was used to assess the association between dental erosion incidence and explanatory variables, with adjusted incidence risk ratios (IRR) and 95% CI estimated. Among those who did not have dental erosion at baseline, 49 of 680 schoolchildren (7.1%; 95% CI=5.2-9.1) developed erosive lesions over the follow-up period. Among schoolchildren who had dental erosion at baseline, 31 of 121 (25.4%; 95% CI=17.6-33.3) had new or more severe lesions. Boys were more likely to develop dental erosion than girls (IRR=1.88; 95% CI=1.06-3.32). A moderate incidence of dental erosion was observed among South Brazilian adolescents, with boys being at higher risk. The high progression rate of 25% observed here is very concerning, and it should be taken in consideration when designing preventive strategies for dental erosion. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Erosion and erosion-corrosion

    International Nuclear Information System (INIS)

    Isomoto, Yoshinori

    2008-01-01

    It is very difficult to interpret the technical term of erosion-corrosion' which is sometimes encountered in piping systems of power plants, because of complicated mechanisms and several confusing definitions of erosion-corrosion phenomena. 'FAC (flow accelerated corrosion)' is recently introduced as wall thinning of materials in power plant systems, as a representative of 'erosion-corrosion'. FAC is, however, not necessarily well understood and compared with erosion-corrosion. This paper describes firstly the origin, definition and fundamental understandings of erosion and erosion-corrosion, in order to reconsider and reconfirm the phenomena of erosion, erosion-corrosion and FAC. Next, typical mapping of erosion, corrosion, erosion-corrosion and FAC are introduced in flow velocity and environmental corrosiveness axes. The concept of damage rate in erosion-corrosion is finally discussed, connecting dissolution rate, mass transfer of metal ions in a metal oxide film and film growth. (author)

  19. Thin layer activation: measuring wear and corrosion

    International Nuclear Information System (INIS)

    Delvigne, T.; Leyman, D.; Oxorn, K.

    1995-01-01

    The technique known as thin layer activation (TLA) is explained and assessed in this article. Widely used, in for example the automotive industry, TLA allows on-line monitoring of the loss of matter from a critical surface, by wear erosion and corrosion. The technique offers extremely high sensitivity thus leading to reduced test times. On-line wear phenomena can be assessed during operation of a mechanical process, even through thick engine walls. (UK)

  20. Influence of anti-corrosion additive on the performance, emission and engine component wear characteristics of an IDI diesel engine fueled with palm biodiesel

    International Nuclear Information System (INIS)

    Ashraful, A.M.; Masjuki, H.H.; Kalam, M.A.; Rashedul, H.K.; Sajjad, H.; Abedin, M.J.

    2014-01-01

    Highlights: • Maximum engine performance was obtained at 2000 rpm for all fuel blends. • IRGALUBE 349 additive is enhances diesel engine performance. • Reduction of CO and NOx considerably using anti-corrosion additive except HC. • Engine wear decreases with using blended fuels with anti-corrosion additive. - Abstract: This study evaluates the effect of anti-corrosion additives such as 8% and 16% (vol.%) palm olein oil (PO) with ordinary diesel (OD) fuel on engine operation, emission behavior, engine part wear, and lubrication characteristics. This experiment was conducted on 4-cylinder and 4-stroke IDI diesel engine at different engine speed ranging from 1200 to 2800 RPM with 30% throttle setting under full load condition. The properties of the palm olein oil blends meet the ASTM D6751 and EN 14214 standards. At 2000 rpm, the experimental results revealed that the POD8A (0.2% Additive + 8% PO + 92% OD) and POD16A (0.2% Additive + 16% PO + 84% OD) blended fuels produced 0.5% and 0.51% higher brake power as well as 1.45% and 1.25% higher torque than same blends without additive, respectively. In comparison with ODF, the brake specific fuel consumption (BSFC) was found 1.8% and 3.1% higher for POD8A and POD16A blends, respectively. Anti-corrosion additive is found more effectual in enhancing the engine performance as such additive helps in timely ignition for complete burn in the combustion chamber. The results from engine emission indicated that POD8A and POD16A blended fuel reduced CO emissions by 11% and 6.6% and NOx emission by 2.5% and 1.09%, respectively in compared with OD fuel. Although HC emissions for all blended fuel and OD fuel increased at higher engine speed, the average HC emissions of all blended fuel were not higher than OD fuel. The application of anti-corrosion additives in POD blends reduced ferrous (Fe) wear debris concentration (WBC) by 17.3%. The reductions in WBC were about 16.1%, 10.8%, and 19.3%, 17.6% for copper (Cu) and aluminum

  1. Effects of pH-Induced Changes in Soil Physical Characteristics on the Development of Soil Water Erosion

    Directory of Open Access Journals (Sweden)

    Shinji Matsumoto

    2018-04-01

    Full Text Available Soil water erosion is frequently reported as serious problem in soils in Southeast Asia with tropical climates, and the variations in pH affect the development of the erosion. This study investigated the effects of changes in pH on soil water erosion based on changes in the physical properties of the simulated soils with pH adjusted from 2.0 to 10.0 through artificial rainfall tests. The zeta potential was entirely shifted to positive direction at each pH condition due to Al, Ca, and Mg. In the pH range of 6.0 to 2.0, the aggregation of soil particles resulting from the release of Al3+ from clay minerals and/or molecular attraction between soil particles caused the plastic index (IP of the soil to decrease. The decrease in IP led to the development of soil water erosion at the pH range. When the pH exceeded 6.0, the repulsive force generated by the negative charges on soil particles decreased IP, resulting in accelerated erosion by water. The results suggest that changes in pH causes physical properties of the soil to change through changes of the zeta potential in the clayey soil rich in Al, Ca, and Mg, leading to the development of soil water erosion.

  2. [Sediment transport characteristics at different erosion stages for non-hardened roads of the Shenfu Coalfield, west China].

    Science.gov (United States)

    Guo, Ming-ming; Wang, Wen-long; Li, Jian-ming; Huang, Peng-fei; Zhu, Bao-cai; Wang, Zhen; Luo, Ting

    2015-02-01

    Non-hardened roads formed in the production of the Shenfu Coalfield have a unique condition of underlying surface. The road surface is composed of a regolith layer with a certain thickness resulted from long-term rolling and thus, is characterized by weakened anti-scourabilty and anti-erodibility. In contrast, soil layer below the regolith has a higher bulk density and anti-erodibility. The processes of soil erosion on the non-hardened roads exhibit some differences under rainfall condition. The process of sediment transport and the relationship between sediment transport rate and erosion factors at different erosion stages were studied on non-hardened roads with slope degrees ranging from 3° to 12° (3°, 6°, 9°, 12°) by a field experiment under artificial rainfall. Results showed that the first peak of sediment transport on the regolith surface was observed at the sheet erosion stage. Sheet erosion occurred only at 3° slope degree, with an average variation coefficient of 0.07 for sediment transport rate. Rills in every testing began to develop at slope degrees of 6° to 12° about 15 min after runoff initiation. At the sheet erosion stage, the process of sediment transport fluctuated considerably at rainfall intensities of > 1.5 mm · min(-1), but the differences in its variation were little at the three slope degrees, with average variation coefficients of 0.20, 0.19 and 0.16, respectively. Rainfall intensity had a more significant impact on sediment transport rate than slope degree. The process of sediment transport at the rill erosion stage fluctuated, but the fluctuation was obviously smaller than that at the sheet erosion stage, with average variation coefficients of 0.05, 0.09 and 0.10 at the three slope degrees. Many wide and shallow rills evolved at the rill erosion stage. The sediment transport rate could be well predicted by a power function of rainfall intensity and slope degree at the sheet and rill erosion stages. The stable sediment transport

  3. Study on erosion behaviour of hybrid aluminium composite

    Science.gov (United States)

    Vishwas, D. K.; Chandrappa, C. N.; Venkatesh, Shreyas

    2018-04-01

    The origin of the light metals, as compared to other metals in this century, is noticeable and an exciting area of expansion for innovation. Light metals, are need of the day in engineering, among them application of aluminium and its alloys is enormous. we observe that these metals tend to have a progressive loss of metal from having contact surface with other metals. Erosion is one such wear process, where damage occurs by the repeated application of high localised stresses. Erosion due to impact of solid particle, is a significant problem. In the present work, the erosion behaviour of hybrid aluminium composite is studied. AL 6061 is used as the base alloy. AL 6061 alloy has excellent corrosion resistance but poor wear resistance. So, in order to have improved properties, it is reinforced with Tungsten Chromium Nickel powder in varied proportions by the method of stir casting. The results are compared with the as-cast Al-alloy to determine the improvement in mechanical properties. The tests were conducted in ASTM G76 setup, to determine solid particle erosion behaviour and the results of the hybrid composite were compared with that of as-cast AL 6061 alloy. It was evident that mass loss was maximum at 300 inclinations, which is a characteristic of ductile materials. It was observed that upon increasing the percentages of reinforcement (wt.%), the wear resistance of the hybrid composite increased significantly. It was also observed that the inclusion of tungsten-chromium-nickel powder increased the hardness of the hybrid composite significantly.

  4. Wear characteristics of TiO[sub 2] coating and silicon carbide alloyed layer on Ti-6Al-4V material

    Energy Technology Data Exchange (ETDEWEB)

    Karamis, M.B. (Dept. of Mechanical Engineering, Erciyes Univ., Kayseri (Turkey))

    1992-08-14

    Wear properties of Ti-6Al-4V material (IMI-318) TiO[sub 2] coated and electron beam alloyed with silicon carbide were tested. Thickness of oxide coating, alloying conditions and properties of the alloyed layer such as hardness, layer thickness and microstructure are described. Wear tests were carried out on a general-purpose wear machine by using a disc-disc sample configuration under lubricated conditions. Counterface materials to oxide-coated and to surface-alloyed specimens were plasma-nitrided AISI 51100 and hardened AISI 4140 respectively. The resulting weight loss and wear resistance were monitored as a function of sliding distance and applied load. Although the electron beam alloying improved the wear resistance of Ti-6Al-4V material, the oxide coatings on the material were not resistant to wear. (orig.).

  5. Experimental Rock-on-Rock Abrasive Wear Under Aqueous Conditions: its Role in Subglacial Abrasion

    Science.gov (United States)

    Rutter, E. H.; Lee, A. G.

    2003-12-01

    We have determined experimentally the rate of abrasive wear of rock on rock for a range of rock types as a function of normal stress and shear displacement. Unlike abrasive wear in fault zones, where wear products accumulate as a thickening gouge zone, in our experiments wear particles were removed by flowing water. The experiments are thus directly pertinent to one of the most important processes in subglacial erosion, and to some extent in river incision. Wear was produced between rotating discs machined from rock samples and measured from the progressive approach of the disc axes towards each other under various levels of normal load. Shear displacements of several km were produced. Optical and scanning electron microscopy were used to study the worn rock surfaces, and particle size distributions in wear products were characterized using a laser particle size analyzer. Rock types studied were sandstones of various porosities and cement characteristics, schists and a granite. In all cases abrasion rate decreased logarithmically with displacement by up to 2 orders of magnitude until a steady state was approached, but only after at least 1 km displacement. The more porous, less-well cemented rocks wore fastest. Amount of abrasion could be characterized quantitatively using an exponentially decaying plus a steady-state term. Wear rate increased non-linearly with normal contact stress, apparently to an asymptote defined by the unconfined compressive strength. Microstructural study showed that the well-cemented and/or lowest porosity rocks wore by progressive abrasion of grains without plucking, whereas whole grains were plucked out of weakly-cemented and/or more porous rocks. This difference in behavior was reflected in wear-product particle size distributions. Where whole-grain plucking was possible, wear products were dominated by particles of the original grain size rather than finer rock flour. Comparison of our results to glacier basal abrasive wear estimated

  6. Far-Infrared Emission Characteristics and Wear Comfort Property of ZrC-Imbedded Heat Storage Knitted Fabrics for Emotional Garments

    Directory of Open Access Journals (Sweden)

    Kim Hyun Ah

    2017-06-01

    Full Text Available This study examined the far-infrared emission characteristics and wear comfort properties of ZrC-imbedded heat storage knitted fabrics. For this purpose, ZrC-imbedded, heat storage PET (polyethylene terephthalate was spun from high-viscosity PET with imbedded ZrC powder on the core part and low-viscosity PET on the sheath part using a conjugated spinning method. ZrC-imbedded PET knitted fabric was also prepared and its physical properties were measured and compared with those of regular PET knitted fabric. In addition, ingredient analysis and the far-infrared emission characteristics of the ZrC-imbedded knitted fabrics were analyzed by energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. The thermal properties, moisture absorption, and drying properties of the ZrC-imbedded PET knitted fabric were measured and compared with those of the regular PET knitted fabric. The mechanical properties using the FAST (fabric assurance by simple testing system and the dye affinity of the ZrC-imbedded knitted fabric were also measured and compared with those of regular PET knitted fabric.

  7. Corneal erosions, bacterial contamination of contact lenses, and microbial keratitis.

    Science.gov (United States)

    Willcox, Mark D P; Naduvilath, Thomas J; Vaddavalli, Pravin K; Holden, Brien A; Ozkan, Jerome; Zhu, Hua

    2010-11-01

    To estimate the rate of corneal erosion coupled with gram-negative bacterial contamination of contact lenses and compare this with the rate of microbial keratitis (MK) with contact lenses. The rate of corneal erosion and contact lens contamination by gram-negative bacteria were calculated from several prospective trials. These rates were used to calculate the theoretical rate of corneal erosion happening at the same time as wearing a contact lens contaminated with gram-negative bacteria. This theoretical rate was then compared with the rates of MK reported in various epidemiological and clinical trials. Corneal erosions were more frequent during extended wear (0.6-2.6% of visits) compared with daily wear (0.01-0.05% of visits). No corneal erosions were observed for lenses worn on a daily disposable basis. Contamination rates for lenses worn on a daily disposable basis were the lowest (2.4%), whereas they were the highest for low Dk lenses worn on an extended wear basis (7.1%). The estimated rate of corneal erosions occurring at the same time as wearing lenses contaminated with gram-negative bacteria was the lowest during daily wear of low Dk lenses (1.56/10,000 [95% CI: 0.23-10.57]) and the highest during extended wear of high Dk lenses (38.55/10,000 [95% CI: 24.77-60.04]). These rates were similar in magnitude to the rates reported for MK of different hydrogel lenses worn on differing wear schedules. The coincidence of corneal erosions during lens wear with gram-negative bacterial contamination of lenses may account for the relative incidence of MK during lens wear with different lens materials and modes of use.

  8. Radioisotopic measurement methods for determining the wear railway brake shoe and its rim wearing effect

    International Nuclear Information System (INIS)

    Doman, P.

    1979-01-01

    Under operating conditions the wear of brake shoe was tested by a measuring method based on the principle of radioisotopic thickness measurement. It is characteristic to the sensitivity of the method that the wear caused by the fast braking of a train (speed: 100 km/h) as well as the uneven wear distribution were determinable. Surface activating methods assuring the periodic and continuous evaluation were also developed. A test was performed with galvanic surface activation under operating conditions to determine the rim wearing effect of the brake shoe. Apart from the operational tests a new method based on activated wear measurement was also developed. (author)

  9. development and performance evaluation of an abrasive wear

    African Journals Online (AJOL)

    User

    advanced countries are not available in Ghana. This makes ... experiment was arranged in a completely randomized design with the soils from the five sites as ... Design of the wear equipment ..... tion of Wear Characteristics of Drill Cultures.

  10. DENTAL EROSION IN PRIMARY DENTITION- A REVIEW

    Directory of Open Access Journals (Sweden)

    Rafi Shaik

    2017-06-01

    Full Text Available BACKGROUND The pattern of oral diseases has been influenced by ever changing human lifestyle. Tooth wear especially dental erosion has drawn increasing attention as risk factor for tooth damage or loss in recent years. It is a common condition in primary dentition compared to permanent dentition due to thinner and less mineralised enamel. However, it is more worrying, when this condition is being found in an alarming proportion among children. The presence of dental erosion in children is likely to be associated with a number of general health and dietary factors, but it is also aggravated by the relatively more rapid progression of erosion in the deciduous teeth. An understanding of the aetiologies and risk factors for erosion is important for early recognition of dental erosion to prevent serious irreversible damage to the dentition. This paper discusses the erosion in children with regard to its epidemiology, prevalence, clinical features, measurement and prevention.

  11. Tooth wear and wear investigations in dentistry.

    Science.gov (United States)

    Lee, A; He, L H; Lyons, K; Swain, M V

    2012-03-01

    Tooth wear has been recognised as a major problem in dentistry. Epidemiological studies have reported an increasing prevalence of tooth wear and general dental practitioners see a greater number of patients seeking treatment with worn dentition. Although the dental literature contains numerous publications related to management and rehabilitation of tooth wear of varying aetiologies, our understanding of the aetiology and pathogenesis of tooth wear is still limited. The wear behaviour of dental biomaterials has also been extensively researched to improve our understanding of the underlying mechanisms and for the development of restorative materials with good wear resistance. The complex nature of tooth wear indicates challenges for conducting in vitro and in vivo wear investigations and a clear correlation between in vitro and in vivo data has not been established. The objective was to critically review the peer reviewed English-language literature pertaining to prevalence and aetiology of tooth wear and wear investigations in dentistry identified through a Medline search engine combined with hand-searching of the relevant literature, covering the period between 1960 and 2011. © 2011 Blackwell Publishing Ltd.

  12. EFFECTS OF SLOPE SHAPES ON SOIL EROSION

    Directory of Open Access Journals (Sweden)

    Hüseyin ŞENSOY, Şahin PALTA

    2009-01-01

    Full Text Available Water is one of the most important erosive forces. A great number of factors also play a role in erosion process and slope characteristic is also one of them. The steepness and length of the slope are important factors for runoff and soil erosion. Another slope factor that has an effect on erosion is the shape of the slope. Generally, different erosion and runoff characteristics exist in different slopes which can be classified as uniform, concave, convex and complex shape. In this study, the effects of slope shape on erosion are stated and emphasized by taking similar researches into consideration.

  13. Truck tyre wear assessment and prediction

    NARCIS (Netherlands)

    Lupker, H.A.; Montanaro, F.; Donadio, D.; Gelosa, E.; Vis, M.A.

    2002-01-01

    Tyre wear is a complex phenomenon. It depends non-linearly on numerous parameters, like tyre compound and design, vehicle type and usage, road conditions and road surface characteristics, environmental conditions (e.g., temperature) and many others. Yet, tyre wear has many economic and ecological

  14. The endoscopic and clinical characteristics of patients with erosive reflux disease diagnosed in gastroscopy unit of a regional hospital

    Directory of Open Access Journals (Sweden)

    Mustafa Yakut

    2012-06-01

    Full Text Available Objectives: Gastroesophageal reflux disease (GERDis a common gastrointestinal disorder, presenting witha broad spectrum of symptoms and can be associatedwith a variety of complication. It has been defined intothree groups of patients: nonerosive reflux disease, erosiveesophagitis, and Barrett’s esophagus. The aim of thestudy was to evaluate patients with erosive reflux diseasein our endoscopic unit.Materials and methods: All patients underwent gastroscopywere evaluated retrospectively. H.pylori statuseswere evaluated in erosive reflux disease (ERD patients.All patients were evaluated by videoendoscopy. Evaluationwas made by the same operator at single center.Biopsy specimen was taken for H.pylori. Diagnosis ofesophagitis was done based on Los Angeles classificationcriteria.Results: All patients that underwent gastroscopy in ourEndoscopy Unit are evaluated. Endoscopically ERD wasdetected in 104 (13.5% of 773 patients. The mean age ofthe ERD patients evaluated in the study was 43.74±18.79years. Sixty five (62.3% patients were female, and 39(38.7% were male. In 104 patients with ERD, the slidinghiatal hernia and Barrett’s esophagus was seen in 18 and10 patients, respectively. H.pylori was positive in 50.9% of104 ERD patients.Conclusion: GERD is a common gastrointestinal disorderand should always be considered during gastroscopy.J Clin Exp Invest 2012; 3(2: 260-262

  15. Comparative characteristic and erosion behavior of NiCr coatings deposited by various high-velocity oxyfuel spray processes

    Science.gov (United States)

    Sidhu, Hazoor Singh; Sidhu, Buta Singh; Prakash, S.

    2006-12-01

    The purpose of this study is to analyze and compare the mechanical properties and microstructure details at the interface of high-velocity oxyfuel (HVOF)-sprayed NiCr-coated boiler tube steels, namely ASTM-SA-210 grade A1, ASTM-SA213-T-11, and ASTM-SA213-T-22. Coatings were developed by two different techniques, and in these techniques liquefied petroleum gas was used as the fuel gas. First, the coatings were characterized by metallographic, scanning electron microscopy/energy-dispersive x-ray analysis, x-ray diffraction, surface roughness, and microhardness, and then were subjected to erosion testing. An attempt has been made to describe the transformations taking place during thermal spraying. It is concluded that the HVOF wire spraying process offers a technically viable and cost-effective alternative to HVOF powder spraying process for applications in an energy generation power plant with a point view of life enhancement and to minimize the tube failures because it gives a coating having better resistance to erosion.

  16. Wear mechanisms in ceramic hip implants.

    Science.gov (United States)

    Slonaker, Matthew; Goswami, Tarun

    2004-01-01

    The wear in hip implants is one of the main causes for premature hip replacements. The wear affects the potential life of the prosthesis and subsequent removals of in vivo implants. Therefore, the objective of this article is to review various joints that show lower wear rates and consequently higher life. Ceramics are used in hip implants and have been found to produce lower wear rates. This article discusses the advantages and disadvantages of ceramics compared to other implant materials. Different types of ceramics that are being used are reviewed in terms of the wear characteristics, debris released, and their size together with other biological factors. In general, the wear rates in ceramics were lower than that of metal-on-metal and metal-on-polyethylene combinations.

  17. Wear Characteristics According of Heat Treatment of Si3N4 with Different Amounts of SiO2 Nano-Colloid

    International Nuclear Information System (INIS)

    Ahn, Seok Hwan; Nam, Ki Woo

    2014-01-01

    This study sintered Si 3 N 4 with different amounts of SiO 2 nano-colloid. The surface of a mirror-polished specimen was coated with SiO 2 nano-colloid, and cracks were healed when the specimen was treated at a temperature of 1273 K for 1 h in air. Wear specimen experiments were conducted after heat treatments for 10 min at 1073, 1273, and 1573 K. The heat-treated surface that was coated with the SiO 2 nano-colloid was slightly rougher than the noncoated surface. The oxidation state of the surface according to the heat treatment temperature showed no correlation with the surface roughness. Moreover, the friction coefficient, wear loss, and bending strength were not related to the surface roughness. Si 3 N 4 exhibited an abrasive wear behavior when SKD11 was used as an opponent material. The friction coefficient was proportional to the wear loss, and the bending strength was inversely proportional to the friction coefficient and wear loss. The friction coefficient and wear loss increased with increasing amounts of the SiO 2 nanocolloid. In addition, the friction coefficient was slightly increased by increasing the heat treatment temperature

  18. Progress in Effect of Nano-modified Coatings and Welding Process Parameters on Wear of Contact Tube for Non-copper Coated Solid Wires

    Directory of Open Access Journals (Sweden)

    LI Zhuo-xin

    2017-12-01

    Full Text Available Environment-friendly non-copper coated solid wire is the main developing trend for gas shielded solid wires, whereas wear of contact tube limits their wide application. The effect of nano-modified coatings and welding process parameters on wear of contact tube for non-copper coated solid wires was reviewed. It was found that the wear of contact tube can be reduced due to the formation of tribo-films on the rubbing surfaces of welding wires against contact tube; it is feasible to decrease contact tube wear when non-copper coated solid wires are coated with nano-modified lubricants, thereby displaying excellent lubricating and thermal or electrical conduction characteristics. The wear of contact tube increases with the increase of welding current. The wear of contact tube is worse in direct-current electrode positive (DCEP than in direct-current electrode negative (DCEN. Arc ablation and electrical erosion are the dominant wear mechanisms of contact tube.

  19. Dental Erosion and Medical Conditions: An Overview of Aetiology, Diagnosis and Management.

    Science.gov (United States)

    Paryag, A; Rafeek, R

    2014-09-01

    Tooth wear or tooth surface loss is a normal physiological process and occurs throughout life but is considered pathological when the degree of destruction is excessive or the rate of loss is rapid, causing functional, aesthetic or sensitivity problems. The importance of tooth wear as a dental problem has been increasingly recognized. The findings of a study in Trinidad indicate that the prevalence of tooth wear in a Trinidadian population is comparable to the United Kingdom (UK) and, indeed, that the level of moderate and severe wear is in fact nearly twice as high. The aetiology of tooth wear is attributed to four causes: erosion, attrition, abrasion and abfraction. Erosion is generally considered to be the most prevalent cause of tooth wear in the UK and Europe. Acids that cause dental erosion originate mainly from the diet or the stomach and to a lesser extent, the environment. Underlying medical problems can contribute to the progress of tooth wear due to erosion and the patient may not be aware of these conditions. Moderate to severe tooth wear poses a significant clinical challenge to dental practitioners and may result in treatment that is more complex and costly to the patient both in terms of finances and time spent in the dental chair. This paper provides an overview of aetiology and diagnosis of tooth wear, in particular tooth wear due to erosion, so that medical and dental practitioners may recognize tooth wear early, institute preventive measures and manage patients appropriately.

  20. 3D FEM Simulation of Flank Wear in Turning

    Science.gov (United States)

    Attanasio, Aldo; Ceretti, Elisabetta; Giardini, Claudio

    2011-05-01

    This work deals with tool wear simulation. Studying the influence of tool wear on tool life, tool substitution policy and influence on final part quality, surface integrity, cutting forces and power consumption it is important to reduce the global process costs. Adhesion, abrasion, erosion, diffusion, corrosion and fracture are some of the phenomena responsible of the tool wear depending on the selected cutting parameters: cutting velocity, feed rate, depth of cut, …. In some cases these wear mechanisms are described by analytical models as a function of process variables (temperature, pressure and sliding velocity along the cutting surface). These analytical models are suitable to be implemented in FEM codes and they can be utilized to simulate the tool wear. In the present paper a commercial 3D FEM software has been customized to simulate the tool wear during turning operations when cutting AISI 1045 carbon steel with uncoated tungsten carbide tip. The FEM software was improved by means of a suitable subroutine able to modify the tool geometry on the basis of the estimated tool wear as the simulation goes on. Since for the considered couple of tool-workpiece material the main phenomena generating wear are the abrasive and the diffusive ones, the tool wear model implemented into the subroutine was obtained as combination between the Usui's and the Takeyama and Murata's models. A comparison between experimental and simulated flank tool wear curves is reported demonstrating that it is possible to simulate the tool wear development.

  1. Erosividade e características hidrológicas das chuvas de Rio Grande (RS Erosivity and hydrological characteristics of rainfalls in Rio Grande (RS, Brazil

    Directory of Open Access Journals (Sweden)

    Marcos Gabriel Peñalva Bazzano

    2010-02-01

    ,0 % do intermediário e 24,2 % do atrasado. Da erosividade anual, 49,1 % correspondeu a chuvas do padrão avançado, 28,9 % a chuvas do padrão intermediário e 22,1 % a chuvas do padrão atrasado. O método da distribuição extrema tipo I foi adequado para obter as curvas de intensidade-duração-frequência. Os períodos de retorno da chuva podem ser calculados por meio das equações, utilizando os valores dos parâmetros encontrados, ou pelos gráficos das curvas de intensidade-duração-frequência.Specific rainfall characteristics vary among regions and their erosion potential must be known for the planning of agricultural and civil engineering activities. For Rio Grande (RS, Brazil, the erosivity and relationships with the precipitation and rainfall coefficient, rainfall hydrologic patterns and return period were determined based on rainfall data of 23 years. For each erosive rainfall the segments of the rainfall chart with the same intensity were separated together and the data registered in worksheets. The mean monthly and annual rainfall erosivity, the EI30 index in the International System of Units and the rainfall patterns were estimated using software Chuveros. The mean monthly values of precipitation and erosivity index were expressed as percentage of the mean annual values of these variables, resulting in the curve of accumulated distribution of precipitation and erosivity index in function of time. The rainfall coefficient (Rc was calculated. Pearson correlations and linear regressions between the erosivity index EI30 and the mean annual values of precipitation and rainfall coefficient were calculated. The rainfall return period was calculated for 2, 5, 10, 20, 50, and 100 years. The mean annual value of EI30 was 5135 MJ mm ha-1 h-1, which is to be used as "R" Factor in the Universal Soil Loss Equation (USLE for Rio Grande and surrounding regions with similar climatic conditions. The regression equations for EI30 and precipitation and rainfall

  2. Dental erosion due to lime consumption; review of literature and ...

    African Journals Online (AJOL)

    Background: Dental health is increasingly threatened by dental erosion introduced by today's lifestyle. Extrinsic factor is the most implicated. Few literatures mentioned lime-incited dental erosion. Case Description: A 49 year old woman was referred to our clinic with tooth wear and sensitivity. She was in good health but on ...

  3. A Study on the Sliding/Impact Wear of a Nuclear Fuel Rod in Room Temperature Air: (I) Development of a Test Rig and Characteristic Analysis

    International Nuclear Information System (INIS)

    Lee, Young Ho; Lee, Kang Hee; Kim, Hyung Kyu

    2007-01-01

    A new type of a fretting wear tester has been designed and developed in order to simulate the actual vibration behavior of a nuclear fuel rod for springs/dimples in room temperature. When considering the actual contact condition between fuel rod and spring/dimple, if fretting wear progress due to the Flow-Induced Vibration (FIV) under a specific normal load exerted on the fuel rod by the elastic deformation of the spring, the contacting force between the fuel rod and dimple that were located in the opposite side should be decreased. Consequently, the evaluation of developed spacer grids against fretting wear damage should be performed with the results of a cell unit experiments because the contacting force is one of the most important variables that influence to the fretting wear mechanism. Therefore, it is necessary to develop a new type of fretting test rig in order to simulate the actual contact condition. In this paper, the development procedure of a new fretting wear tester and its performance were discussed in detail

  4. Characteristics of symptomatic reflux episodes in Japanese proton pump inhibitor-refractory non-erosive reflux disease patients

    Science.gov (United States)

    Nakagawa, Kenichiro; Koike, Tomoyuki; Iijima, Katsunori; Saito, Masahiro; Kikuchi, Hiroki; Hatta, Waku; Ara, Nobuyuki; Uno, Kaname; Asano, Naoki; Shimosegawa, Tooru

    2015-01-01

    AIM: To clarify the pathogenesis of gastroesophageal reflux disease symptoms in non-erosive reflux disease (NERD) patients. METHODS: Thirty-five NERD patients with persistent symptoms, despite taking rabeprazole 10 mg twice daily for at least 8 wk, were included in this study. All patients underwent 24 h combined impedance - pH on rabeprazole. The symptom index (SI) was considered to be positive if ≥ 50%, and proximal reflux episodes were determined when reflux reached 15 cm above the proximal margin of the lower esophageal sphincter. RESULTS: In 14 (40%) SI-positive patients, with liquid weakly acid reflux, the occurrence rate of reflux symptoms was significantly more frequent in proximal reflux episodes (46.7%) than in distal ones (5.7%) (P acid reflux, there were no significant differences in the occurrence rate of reflux symptoms between proximal reflux episodes (38.5%) and distal ones (20.5%) (NS). With mixed liquid-gas weakly acid reflux, the occurrence rate of reflux symptoms in proximal reflux episodes was significantly more frequent (31.0%) than in distal reflux ones (3.3%) (P acid reflux, there were no significant differences in the occurrence rate of reflux symptoms between proximal reflux episodes (29.4%) and distal ones (14.3%) (NS). CONCLUSION: The proximal extent of weakly acidic liquid and mixed liquid-gas reflux is a major factor associated with reflux perception in SI-positive patients on proton pump inhibitor therapy. PMID:26715820

  5. Association between Severity of Tooth Wear and Dentinal Hypersensitivity

    Directory of Open Access Journals (Sweden)

    Ashok Ayer

    2016-11-01

    Full Text Available Background & Objectives: Tooth wear (attrition, abrasion, erosion, and abfraction is perceived globally as ever increasing problem. Several outcome of the tooth wear are hypersensitivity, esthetic problems, functional impairment, annoyance to the patient, and fracture of the tooth. Among these, the measurable and more commonly reported outcome is hypersensitivity to stimuli. Although dentin hypersensitivity is a common clinical condition and is generally reported by the patient after experiencing a sharp, short pain caused by one of the several different external stimuli, it is often inadequately understood. None of the scientific literature available till date attempted to establish the relationship between tooth wear and dentin hypersensitivity which could be a key factor in monitoring those patients.  The aim of the study was to estimate the association between severity of teeth wear and sensitivity in the patients with reported dentinal hypersensitivity.Materials & Methods: Fifty patients with dentin hypersensitivity were investigated for tooth wear. Tooth wear measured using exact tooth wear index and level of sensitivity to stimuli was recorded using a numerical rating scale. Results: Enamel wear at cervical region of teeth showed a positive correlation (p=.010, similarly, dentin wear at cervical region of teeth showed positive correlation and significant association (p<.001 with dentinal hypersensitivity.Conclusion: The observation supports a significant association between severities of tooth surface wear and dentinal hypersensitivity.

  6. Medication-related dental erosion: a review.

    Science.gov (United States)

    Thomas, Manuel S; Vivekananda Pai, A R; Yadav, Amit

    2015-10-01

    Dental erosion has become a major problem that affects the long-term health of the dentition. Among the various potential causes for erosive tooth wear, the different drugs prescribed for patients may be overlooked. Several therapeutic medications can directly or indirectly be associated with dental erosion. It is the responsibility of oral health providers to make both patients and colleagues aware of drugs that may contribute to this condition. Therefore, the purpose of this discussion is to provide an overview of the various therapeutic medications that can be related to tooth erosion. The authors also include precautionary measures-summarized as The 9 Rs-to avoid or at least reduce medication-induced erosion.

  7. Lava channel formation during the 2001 eruption on Mount Etna: evidence for mechanical erosion.

    Science.gov (United States)

    Ferlito, Carmelo; Siewert, Jens

    2006-01-20

    We report the direct observation of a peculiar lava channel that was formed near the base of a parasitic cone during the 2001 eruption on Mount Etna. Erosive processes by flowing lava are commonly attributed to thermal erosion. However, field evidence strongly suggests that models of thermal erosion cannot explain the formation of this channel. Here, we put forward the idea that the essential erosion mechanism was abrasive wear. By applying a simple model from tribology we demonstrate that the available data agree favorably with our hypothesis. Consequently, we propose that erosional processes resembling the wear phenomena in glacial erosion are possible in a volcanic environment.

  8. Erosion resistance comparison of alternative surface treatments

    Science.gov (United States)

    Česánek, Z.; Schubert, J.; Houdková, Š.

    2017-05-01

    Erosion is a process characterized by the particle separation and the damage of component functional surfaces. Thermal spraying technology HP/HVOF (High Pressure / High Velocity Oxygen Fuel) is commonly used for protection of component surfaces against erosive wear. Alloy as well as cermet based coatings meet the requirements for high erosion resistance. Wear resistance is in many cases the determining property of required component functioning. The application suitability of coating materials is particularly influenced by different hardness. This paper therefore presents an erosion resistance comparison of alloy and cermet based coatings. The coatings were applied on steel substrates and were subjected to the erosive test using the device for evaluation of material erosion resistance working on the principle of centrifugal erodent flow. Abrasive sand Al2O3 with grain size 212-250 μm was selected as an erosive material. For this purpose, the specimens were prepared by thermal spraying technology HP/HVOF using commercially available powders Stellite 6, NiCrBSi, Cr3C2-25%NiCr, Cr3C2-25%CoNiCrAlY, Hastelloy C-276 and experimental coating TiMoCN-29% Ni. Erosion resistance of evaluated coatings was compared with erosive resistance of 1.4923 high alloyed steel without nitridation and in nitrided state and further with surface treatment using technology PVD. According to the evaluation, the resulting erosive resistance depends not only on the selected erodent and surface protection, but also on the erodent impact angle.

  9. Study on influence of Surface roughness of Ni-Al2O3 nano composite coating and evaluation of wear characteristics

    Science.gov (United States)

    Raghavendra, C. R.; Basavarajappa, S.; Sogalad, Irappa

    2018-02-01

    Electrodeposition is one of the most technologically feasible and economically superior techniques for producing metallic coating. The advancement in the application of nano particles has grabbed the attention in all fields of engineering. In this present study an attempt has been made on the Ni-Al2O3nano particle composite coating on aluminium substrate by electrodeposition process. The aluminium surface requires a specific pre-treatment for better adherence of coating. In light of this a thin zinc layer is coated on the aluminium substrate by electroless process. In addition to this surface roughness is an important parameter for any coating method and material. In this work Ni-Al2O3 composite coating were successfully coated by varying the process parameters such as bath temperature, current density and particle loading. The experimentation was performed using central composite design based 20 trials of experiments. The effect of process parameters and surface roughness before and after coating is analyzed on wear rate and coating thickness. The results shown a better wear resistance of Ni-Al2O3 composite electrodeposited coating compared to Ni coating. The particle loading and interaction effect of current density with temperature has greater significant effect on wear rate. The surface roughness is significantly affected the wear behaviour and thickness of coating.

  10. Abrasive wear of intermetallics

    International Nuclear Information System (INIS)

    Hawk, J.A.; Alman, D.E.; Wilson, R.D.

    1995-01-01

    The US Bureau of Mines is investigating the wear behavior of a variety of advanced materials. Among the many materials under evaluation are intermetallic alloys based on the compounds: Fe 3 Al, Ti 3 Al, TiAl, Al 3 Ti, NiAl and MoSi 2 . The high hardness, high modulus, low density, and superior environmental stability of these compounds make them attractive for wear materials. This paper reports on the abrasive wear of alloys and composites based on the above compounds. The abrasive wear behavior of these alloys and composites are compared to other engineering materials used in wear applications

  11. [Distribution characteristics and erosion risk of nitrogen and phosphorus in soils of Zhuangmu town in Lake Wabuhu basin].

    Science.gov (United States)

    Li, Ru-Zhong; Zou, Yang; Xu, Jing-Jing; Ding, Gui-Zhen

    2014-03-01

    To understand the loss risk of soil erosion in the Zhuangmu town in Lake Wabuhu watershed, concentration and spatial distribution of nitrogen and phosphorus in 162 surface soil samples collected from the farmlands in ten administrative villages of the town were investigated. The risk assessment was conducted by using the nitrogen and phosphorus index method after speciation analysis of soil nitrogen and phosphorus. Based on ArcGIS technology, the spatial interpolation of total nitrogen (TN), total phosphorus (TP), and bioavailable nitrogen and phosphorus contents as well as nitrogen and phosphorus index values were performed by means of Kriging interpolation. The results show that, generally, average contents of TN and TP were obtained at 1.67 g x kg(-1) and 0.71 g x kg(-1), respectively. And the mean concentration of bioavailable nitrogen and phosphorus were estimated at 0.26 g x kg(-1) and 0.33 g x kg(-1), accounting for 14.93% and 47.30% of TN and TP contents, respectively. Spatially, the samples with high concentration of TN were mostly from Houji, Yangwan and Liuqian villages, whereas the samples sites with higher contents of TP located in Houji, Yangwan and Zaolin villages. The mean values of nitrogen index (NI) and phosphorus index (PI) for the whole town are 2.11 and 2.13, respectively. According to the numeric size of NI and PI, ten villages ranged in the order of Yangwan > Zhuangmu > Xueqiao > Liuqian > Lizhuang > Jinqiao > Zaolin > Zhangwei > Houji > Xugang village. In general, the soil nitrogen loss is dominated by low and medium risks in the Zhuangmu town, and high risk sporadically appears in local area of the Yangwan village. Like the nitrogen, soil phosphorus loss risk also gives priority to low, and above medium risk concentrates in the Yangwan village as well.

  12. Protection From Dental Erosion: All Fluorides are Not Equal.

    Science.gov (United States)

    Faller, Robert V; Noble, Warden H

    2018-03-01

    All fluoride sources help strengthen teeth against bacterial acids that cause caries. However, excessive exposure to dietary acids, which can result in dental erosion, presents a more aggressive level of challenge compared to caries. Despite the fact that almost all toothpastes contain fluoride, both the incidence and prevalence of dental erosion appear to be on the rise. This article: (1) describes key differences between caries and dental erosion and the ability of different fluoride sources to help prevent erosion; (2) discusses the importance of the evaluation of patients for dental erosion at the earliest stages using the Basic Erosive Wear Examination scoring system to help assess and educate patients; and (3) provides evidence-based information for making specific recommendations to patients with dental erosion. The objective of this article is to assess the comparative ability of fluoride agents to protect against dental erosion. Though all fluorides are able to help strengthen teeth against cariogenic acids, not all available sources of fluoride provide the same level of erosion protection. Daily use of a stabilized stannous fluoride dentifrice has been shown to provide the most effective means of protecting teeth against the increasing risk of dental erosion and erosive tooth wear.

  13. Comparison of erosion and erosion control works in Macedonia, Serbia and Bulgaria

    Directory of Open Access Journals (Sweden)

    Ivan Blinkov

    2013-12-01

    Natural conditions in the Balkan countries contribute to the appearance of various erosion forms and the intensity of the erosion processes. Over the history of these countries, people who settled this region used the available natural resources to fill their needs (tree cutting, incorrect plugging, overgrazing, which contributed to soil erosion. Organized erosion control works in the Balkans started in the beginning of the 20th century (1905 in Bulgaria. The highest intensity of erosion control works were carried out during the period 1945 – 1990. Various erosion control works were launched. Bulgaria had a large anti-erosion afforestation, almost 1 million ha. Bulgaria's ecological river restoration approach has been in use for almost 50 years. Serbia contributed significant erosion and torrent control works on hilly agricultural areas. Specific screen barrages and afforestation on extremely dry areas are characteristic in Macedonia. A common characteristic for all countries is a high decrease in erosion control works in the last 20 years.

  14. RESISTENCIA AL DESGASTE EROSIVO-CORROSIVO DE ACEROS AUSTENÍTICOS FERMANAL RESISTÊNCIA AO DESGASTE EROSIVO-CORROSIVO DE AÇOS AUSTENÍTICOS FERMANAL EROSIVE-CORROSIVE WEAR RESISTANCE OF FERMANAL AUSTENITIC STEELS

    Directory of Open Access Journals (Sweden)

    Willian Aperador

    2012-12-01

    the range (4.9~11.0 wt% Al - (17.49~34.3 wt% Mn - (0, 43~1.25 wt% C, which were melted in an induction furnace from high purity materials. The alloys were evaluated with respect to corrosion, wet erosion and corrosion-erosion at an impact angle of 90°. For the evaluation of corrosion a solution composed of 0.5 M NaCl and silica particles with size between 210 to 300 microns was used in order to analyze the effect of aluminum and manganese content in the resistance to erosion and corrosion-erosion of these alloys. To characterize the corrosion, response technique was used by potentiodynamic polarization curves and using the same technique as Tafel extrapolation, the microstructural characterization by scanning electron microscopy (SEM, and the composition of corrosion products were analyzed using diffraction of X-rays (XRD.

  15. Dental Wear: A Scanning Electron Microscope Study

    Directory of Open Access Journals (Sweden)

    Luca Levrini

    2014-01-01

    Full Text Available Dental wear can be differentiated into different types on the basis of morphological and etiological factors. The present research was carried out on twelve extracted human teeth with dental wear (three teeth showing each type of wear: erosion, attrition, abrasion, and abfraction studied by scanning electron microscopy (SEM. The study aimed, through analysis of the macro- and micromorphological features of the lesions (considering the enamel, dentin, enamel prisms, dentinal tubules, and pulp, to clarify the different clinical and diagnostic presentations of dental wear and their possible significance. Our results, which confirm current knowledge, provide a complete overview of the distinctive morphology of each lesion type. It is important to identify the type of dental wear lesion in order to recognize the contributing etiological factors and, consequently, identify other more complex, nondental disorders (such as gastroesophageal reflux, eating disorders. It is clear that each type of lesion has a specific morphology and mechanism, and further clinical studies are needed to clarify the etiological processes, particularly those underlying the onset of abfraction.

  16. Impact of soil characteristics and land use on pipe erosion in a temperate humid climate: Field studies in Belgium

    Science.gov (United States)

    Verachtert, E.; Van Den Eeckhaut, M.; Martínez-Murillo, J. F.; Nadal-Romero, E.; Poesen, J.; Devoldere, S.; Wijnants, N.; Deckers, J.

    2013-06-01

    This study investigates the role of soil characteristics and land use in the development of soil pipes in the loess belt of Belgium. First, we tested the hypothesis that discontinuities in the soil profile enhance lateral flow and piping by impeding vertical infiltration. We focus on discontinuities in soil characteristics that can vary with soil depth, including texture, saturated hydraulic conductivity, penetration resistance, and bulk density. These characteristics as well as soil biological activity were studied in detail on 12 representative soil profiles for different land use types. Twelve sites were selected in the Flemish Ardennes (Belgium): four pastures with collapsed pipes (CP), four pastures without CP, two sites under arable land without CP and two sites under forest without CP. Secondly, this study aimed at evaluating the interaction of groundwater table positions (through soil augerings) and CP in a larger area, with a focus on pastures. Pasture is the land use where almost all CP in the study area are observed. Therefore, the position of the groundwater table was compared for 15 pastures with CP and 14 pastures without CP, having comparable topographical characteristics in terms of slope gradient and contributing area. Finally, the effect of land use history on the occurrence of pipe collapse was evaluated for a database of 84 parcels with CP and 84 parcels without CP, currently under pasture. As to the first hypothesis, no clear discontinuities for abiotic soil characteristics in soil profiles were observed at the depth where pipes occur, but pastures with CP had significantly more earthworm channels and mole burrows at larger depths (> 120 cm: mean of > 200 earthworm channels per m2) than pastures without CP, arable land or forest (> 120 cm depth, a few or no earthworm channels left). The land use history appeared to be similar for the pastures with and without CP. Combining all results from soil profiles and soil augering indicates that intense

  17. Erhversbetinget erosion?

    DEFF Research Database (Denmark)

    Dige, Irene; Gjørup, Hans; Nyvad, Bente

    2012-01-01

    Baggrund – I forbindelse med dental erosion er en grundig udredning af patienten vigtig, således at årsagen til erosionernes opståen findes, og der kan iværksættes adækvat forebyggende indsats. En sådan udredning er ikke mindst vigtig, når arbejdsmiljøet mistænkes. Patienttilfælde – En 30-årig...... arbejdsskade, men ikke anerkendt, da erosioner ikke er optaget på Arbejdsskadestyrelsens liste over erhvervssygdomme. En systematisk registrering af lignende tilfælde kunne imidlertid på sigt ændre retspraksis for fremtidige patienter med arbejdsbetinget erosion....... patient, der arbejder som pladesmed, blev henvist til Landsdels- og Videnscenter, Århus Sygehus, med henblik på udredning af patientens kraftige slid. Patienten udviste ikke-alderssvarende tandslid af emalje og dentin svarende til erosion forårsaget af syredampe i arbejdsmiljøet, muligvis forstærket af...

  18. Polymer wear evaluation

    DEFF Research Database (Denmark)

    Lagerbon, Mikkel; Sivebæk, Ion Marius

    2012-01-01

    Polymer wear plays an increasing role in manufacturing of machine parts for e.g. medical devices. Some of these have an expected lifetime of five to eight years during which very little wear of the components is acceptable. Too much wear compromises the dosage accuracy of the device and thereby...... the safety of the patients. Prediction of the wear of polymers is complicated by the low thermal conductivity of this kind of material. It implies that any acceleration of testing conditions by increased contact pressure and/or sliding velocity will make the polymer fail due to exaggerated heat buildup....... This is not the kind of wear observed in medical devices. In the present work a method was developed capable of evaluating the wear progression in polymer-polymer contacts. The configuration of the setup is injection moulded specimens consisting of an upper part having a toroid shape and a lower flat part. The sliding...

  19. Friction and wear of stainless steel, titanium and aluminium with various surface treatments, ion implantation and overlay hard coatings

    International Nuclear Information System (INIS)

    Bunshah, R.F.

    1979-01-01

    This paper deals with the evaluation of the wear properties of 304 stainless steel, commercial grade titanium and commercial grade aluminium without and with different surface treatments, i.e., ion implantation of boron and nitrogen, and overlay coating of superhard materials, titanium carbide and nitride by the Biased Activated Reactive Evaporation (BARE) process. Wear properties were evaluated in adhesive, erosive and abrasive modes of wear. In the case of adhesive wear, ion implantation resulted in an improved wear behaviour in lubricated conditions but had no beneficial effect in dry wear conditions. Overlay coatings on the other hand resulted in improved wear behaviour for both the dry and lubricating conditions. In the case of erosive wear with SiC particles at high velocities, overlay coatings showed higher erosion rates (typical of brittle materials in normal impingement) whereas ion implanted materials behaved similarly as untreated materials; i.e., a lower wear rate than the specimens with overlay coatings. In the case of abrasive wear, it was again observed that the wear rates of overlay coatings is far lower than the wear rates of untreated or ion implanted materials. (author)

  20. Experimental study of the cavitation erosion in centrifugal pump impeller

    International Nuclear Information System (INIS)

    Rayan, M.A.

    1985-01-01

    Research on cavitation damage scale effects show that the damage rate is increased with size and velocity. It seems that for constant velocity there is no clear trend for the variation of erosion with cavitation number. Research on the time effects on damage rate show similarity between cavitation and impingement erosion. The cumulative weight loss versus time curve is of a ''S'' shaped type characterized by an incubation period followed by a period of increasing erosion rate, then a maximum erosion rate, and finally a period of decreasing erosion rate. The objective of this investigation is to present a prototype cavitation erosion experiment in order to clarify the time dependency of the erosive wear

  1. Anthropology, tooth wear, and occlusion ab origine.

    Science.gov (United States)

    Young, W G

    1998-11-01

    The purpose of this essay is to emphasize that anthropology, the study of man in his environments, is a potent tool for scientific discovery and inspiration in dental science. It attempts to capture flashes of creative anthropological insight which have illuminated studies of tooth wear and occlusion in the past. While it documents contributions, understandings, and misunderstandings from Australian and New Zealand dentists, it is not a hagiography. The real saint of this essay is the Australian aborigine. For when men and women are understood in their environments, much is learned from them which challenges preconceptions of our dental science culture. The essay concludes that new, contemporary Australian culture needs to be studied by anthropological approaches if we are to understand how dental erosion is exacerbating tooth wear and damaging the occlusions of contemporary Australians. Much remains to be discovered about contemporary lifestyles, habits, and diets that lead to dental erosion, the principal cause of contemporary tooth wear in this part of the world.

  2. Research on the effect of wear-ring clearances to the axial and radial force of a centrifugal pump

    International Nuclear Information System (INIS)

    Zhao, W G; Qi, C X; Li, Y B; He, M Y

    2013-01-01

    Varying of the wear-ring clearance not only has a distinct effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump including the axial and radial forces. Comparing with the experimental studies, numerical simulation methods have some special advantages, such as the low cost, fast and high efficiency, and convenient to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study in recent years. In order to study the effect of wear-ring clearance on the force performance of the centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump with three variable styles of the wear-rings was simulated: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Comparing with the experiment, numerical results show a good agreement. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the axial force of the centrifugal pump, while has tiny effect on the radial force for all the conditions

  3. Fiscal 1999 achievement report on regional consortium research and development project. Regional consortium on energy research in its 3rd year (Research and development of mezoscopic composite phase material based on heat-/wear-resistant metal); 1999 nendo mezoscopic fukuso soshiki seigyo tainetsu taimamosei kinzokuki fukugo zairyo no kenkyu kaihatsu seika hokokusho. 3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Using an in-situ method, three kinds of Fe-C-Ni-Cr-Mo-Nb-based alloys are developed, whose strength is not less than 800MPa at 1073K. They exhibit, in a high-temperature erosion wear test, a wear resistance which is 2-3 times higher than that of conventional materials. When they are cast, wear-causing graphite precipitation is suppressed thanks to the cast iron coagulating in gaps in the ceramic formed into a net shape. It is also found that in this process the precipitation of cementites etc., which improves on the abrasion and wear characteristics, is accelerated and that the cementites etc. are finely dispersed for improvement on the brake (brake block) characteristics. Tentatively produced brake blocks are tested for performance at the Railway Technical Research Institute. The new materials are found to exhibit a wear resistance which is 2.2 times higher, and a braking capability 1.6 times better, than those of conventional materials. In the case of an Fe-50Cr-4.8C alloy produced by an MA (mechanical alloying) method, {alpha}-Fe is dispersed into M{sub 23}C{sub 6} for a remarkable improvement on the wear-resisting feature. A 10%TiC cermet exhibits a remarkably high wear resistance, that is, a transverse rupture strength of 1270MPa which is higher than that of a cast high-speed steel. (NEDO)

  4. Dental erosion caused by gastroesophageal reflux disease: a case report

    OpenAIRE

    Cengiz, Seda; Cengiz, M ?nan?; Sara?, Y ?inasi

    2009-01-01

    Introduction Chronic regurgitation of gastric acids in patients with gastroesophageal reflux disease may cause dental erosion, which can lead in combination with attrition or bruxism to extensive loss of coronal tooth tissue. Case presentation This clinical report describes treatment of severe tooth wear of a gastroesophageal reflux disease patient who is 54-year-old Turkish male patient. After his medical treatment, severe tooth wear, bruxism and decreased vertical dimensions were determined...

  5. Effect of size and concentration of silt particles on erosion of Pelton turbine buckets

    Energy Technology Data Exchange (ETDEWEB)

    Padhy, M.K.; Saini, R.P. [Alternate Hydro Energy Centre, Indian Institute of Technology Roorkee, Roorkee (India)

    2009-10-15

    Erosive wear of hydro turbine runners depends upon different parameters such as size, hardness and concentration of silt particles, velocity of flow, properties of the base material of the turbine components and operating hours of the turbine. Various researchers have conducted experiments to study the effect of these parameters on erosive wear. Most of these experiments were on small-size samples at different types of test rigs to simulate the flow conditions in turbines, however actual flow conditions and the phenomenon of erosive wear are too complex to simulate. Under the present study, effect of these parameters on erosion in actual conditions has been investigated experimentally. An extensive experimental study has been carried out on a small scale Pelton turbine. Based on the experimental data collected for different parameters, correlations have been developed for wear rate of Pelton turbine buckets as a function of critical parameters, i.e., size and concentration of silt particles and jet velocity. (author)

  6. Predicting of soil erosion with regarding to rainfall erosivity and soil erodibility

    Science.gov (United States)

    Suif, Zuliziana; Razak, Mohd Amirun Anis Ab; Ahmad, Nordila

    2018-02-01

    The soil along the hill and slope are wearing away due to erosion and it can take place due to occurrence of weak and heavy rainfall. The aim of this study is to predict the soil erosion degree in Universiti Pertahanan Nasional Malaysia (UPNM) area focused on two major factor which is soil erodibility and rainfall erosivity. Soil erodibility is the possibilities of soil to detach and carried away during rainfall and runoff. The "ROM" scale was used in this study to determine the degree of soil erodibility, namely low, moderate, high, and very high. As for rainfall erosivity, the erosive power caused by rainfall that cause soil loss. A daily rainfall data collected from January to April was analyzed by using ROSE index classification to identify the potential risk of soil erosion. The result shows that the soil erodibilty are moderate at MTD`s hill, high at behind of block Lestari and Landslide MTD hill, and critical at behind the mess cadet. While, the highest rainfall erosivity was recorded in March and April. Overall, this study would benefit the organization greatly in saving cost in landslide protection as relevant authorities can take early measures repairing the most affected area of soil erosion.

  7. Sports drink consumption and dental erosion among amateur runners.

    Science.gov (United States)

    Antunes, Leonardo S; Veiga, Lais; Nery, Victor S; Nery, Caio C; Antunes, Lívia A

    2017-01-01

    This cross-sectional study assessed the prevalence and potential risk factors for dental erosion in amateur athletes at running events. After a sample calculation, 108 runners from the state of Rio de Janeiro, Brazil, were selected and examined for dental wear by a single trained and calibrated evaluator (kappa = 1.00). To identify risk factors, the runners were interviewed by using a standardized, semi-structured questionnaire. The average (SD) age of the runners was 34.2 (11.45), and the prevalence of dental erosion was 19.4%. Gastroesophageal reflux, running frequency per week, and time expended during competition were associated with dental erosion (P dental erosion was not significant (P > 0.05). In conclusion, dental erosion was not associated with use of isotonic drinks. However, frequency of exercise per week and gastroesophageal reflux were risk factors for dental erosion.

  8. Simulation of erosion by a particulate airflow through a ventilator

    Science.gov (United States)

    Ghenaiet, A.

    2015-08-01

    Particulate flows are a serious problem in air ventilation systems, leading to erosion of rotor blades and aerodynamic performance degradation. This paper presents the numerical results of sand particle trajectories and erosion patterns in an axial ventilator and the subsequent blade deterioration. The flow field was solved separately by using the code CFX- TASCflow. The Lagrangian approach for the solid particles tracking implemented in our inhouse code considers particle and eddy interaction, particle size distribution, particle rebounds and near walls effects. The assessment of erosion wear is based on the impact frequency and local values of erosion rate. Particle trajectories and erosion simulation revealed distinctive zones of impacts with high rates of erosion mainly on the blade pressure side, whereas the suction side is eroded around the leading edge.

  9. Composition of enamel pellicle from dental erosion patients.

    Science.gov (United States)

    Carpenter, G; Cotroneo, E; Moazzez, R; Rojas-Serrano, M; Donaldson, N; Austin, R; Zaidel, L; Bartlett, D; Proctor, G

    2014-01-01

    Oral health is dependent upon a thin mobile film of saliva on soft and hard tissues. Salivary proteins adhere to teeth to form the acquired enamel pellicle which is believed to protect teeth from acid erosion. This study investigated whether patients suffering diet-induced dental erosion had altered enamel pellicles. Thirty patients suffering erosion were compared to healthy age-matched controls. Subjects wore a maxillary splint holding hydroxyapatite and human enamel blocks for 1 h. The acquired enamel pellicle was removed from the blocks and compared to the natural incisor pellicle. Basic Erosive Wear Examination scores confirmed that dental erosion was present in erosion patients and absent from healthy age-matched controls. Erosion patients had half the amount of proteins (BCA assay) within the acquired pellicle forming on splint blocks compared to normal controls (p erosion patients (p erosion patients and healthy controls. In summary, the formation of new acquired pellicles on surfaces was reduced in erosion patients, which may explain their greater susceptibility to acid erosion of teeth. © 2014 S. Karger AG, Basel.

  10. Wet-steam erosion of steam turbine disks and shafts

    International Nuclear Information System (INIS)

    Averkina, N. V.; Zheleznyak, I. V.; Kachuriner, Yu. Ya.; Nosovitskii, I. A.; Orlik, V. G.; Shishkin, V. I.

    2011-01-01

    A study of wet-steam erosion of the disks and the rotor bosses or housings of turbines in thermal and nuclear power plants shows that the rate of wear does not depend on the diagrammed degree of moisture, but is determined by moisture condensing on the surfaces of the diaphragms and steam inlet components. Renovating the diaphragm seals as an assembly with condensate removal provides a manifold reduction in the erosion.

  11. Erosion on spark plug electrodes; Funkenerosion an Zuendkerzenelektroden

    Energy Technology Data Exchange (ETDEWEB)

    Rager, J.

    2006-07-01

    Durability of spark plugs is mainly determined by spark gap widening, caused by electrode wear. Knowledge about the erosion mechanisms of spark plug materials is of fundamental interest for the development of materials with a high resistance against electrode erosion. It is therefore crucial to identify those parameters which significantly influence the erosion behaviour of a material. In this work, a reliable and reproducible testing method is presented which produces and characterizes electrode wear under well-defined conditions and which is capable of altering parameters specifically. Endurance tests were carried out to study the dependence of the wear behaviour of pure nickel and platinum on the electrode temperature, gas, electrode gap, electrode diameter, atmospheric pressure, and partial pressure of oxygen. It was shown that erosion under nitrogen is negligible, irrespective of the material. This disproves all common mechanism discussed in the literature explaining material loss of spark plug electrodes. Based on this observation and the variation of the mentioned parameters a new erosion model was deduced. This relies on an oxidation of the electrode material and describes the erosion of nickel and platinum separately. For nickel, electrode wear is caused by the removal of an oxide layer by the spark. In the case of platinum, material loss occurs due to the plasma-assisted formation and subsequent evaporation of volatile oxides in the cathode spot. On the basis of this mechanism a new composite material was developed whose erosion resistance is superior to pure platinum. Oxidation resistant metal oxide particles were added to a platinum matrix, thus leading to a higher erosion resistance of the composite. However, this can be decreased by a side reaction, the separation of oxygen from the metal oxides, which effectively assists the oxidation of the matrix. This reaction can be suppressed by using highly stable oxides, characterized by a large negative Gibbs

  12. Fretting wear damage of steam generator tubes and its prediction modeling

    International Nuclear Information System (INIS)

    Che Honglong; Lei Mingkai

    2013-01-01

    The steam generator is the key equipment used for the energy transition in nuclear power plant. Since the high-temperature and high-pressure fluid flows with high speed, the steam generator tubes will be excited and vibrate, leading to the tremendous fretting wear problem on the tubes, sometimes even leading to tube cracking. This paper introduces typical fretting wear cases, the result of corresponding simulation wear experiment and damage mechanism which combining mechanical wear and erosion-corrosion. Work rate model could give a reasonable life prediction about the steam generator tube, and this predictive model has been used in nuclear power plant safety assessment. (authors)

  13. Preliminary studies for monitoring erosion in pipelines by the acoustic emission technique

    Energy Technology Data Exchange (ETDEWEB)

    Tiboni, G.B. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-graduacao em Engenharia Mecanica e de Materiais; Marquardt, T.A.S; SantaMaria, V.A.R.; Silva, C.H. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)

    2009-07-01

    The aim of this work is to present some applications of Acoustic Emission (AE), which is a powerful technique for nondestructive testing in Tribology, treated here as tests of friction, wear by contact fatigue, wear by slip and wear by erosion. In this work a special attention is given to solid particle erosion and hydro-abrasive erosion, problems found in almost every pipeline that lead to local loss of material and eventually rupture of the line. The technique of AE can be used as an efficient online tool when, primarily, to monitor tribological aspects such as the rate of wear of materials, as well as detect the spread of flaws in them. In wear by erosion, specifically, the parameters of RMS and acoustic energy are capable of correlation with the type of mechanism for removal of material. As a preliminary goal, erosive tests were performed with gas (air) without erosive particles, monitored by AE, varying the surface of the samples and the internal diameter the nozzle, taking the differences in signs of AE. Correlation between parameters of RMS and amplitude were noticed with the variables of the tests, such as roughness and fluid velocity. The RMS parameter showed a exponential correction with the fluid velocity, however the amplitude signals had a linear behavior. The knowledge of these parameters is essential for the development of a system that is able to quantify the wear rate of a pipeline without taking it out of operation. (author)

  14. Wear analysis of disc cutters of full face rock tunnel boring machine

    Science.gov (United States)

    Zhang, Zhaohuang; Meng, Liang; Sun, Fei

    2014-11-01

    Wear is a major factor of disc cutters' failure. No current theory offers a standard for the prediction of disc cutter wear yet. In the field the wear prediction method commonly used is based on the excavation length of tunnel boring machine(TBM) to predict the disc cutter wear and its wear law, considering the location number of each disc cutter on the cutterhead(radius for installation); in theory, there is a prediction method of using arc wear coefficient. However, the preceding two methods have their own errors, with their accuracy being 40% or so and largely relying on the technicians' experience. Therefore, radial wear coefficient, axial wear coefficient and trajectory wear coefficient are defined on the basis of the operating characteristics of TBM. With reference to the installation and characteristics of disc cutters, those coefficients are modified according to penetration, which gives rise to the presentation of comprehensive axial wear coefficient, comprehensive radial wear coefficient and comprehensive trajectory wear coefficient. Calculation and determination of wear coefficients are made with consideration of data from a segment of TBM project(excavation length 173 m). The resulting wear coefficient values, after modification, are adopted to predict the disc cutter wear in the follow-up segment of the TBM project(excavation length of 5621 m). The prediction results show that the disc cutter wear predicted with comprehensive radial wear coefficient and comprehensive trajectory wear coefficient are not only accurate(accuracy 16.12%) but also highly congruous, whereas there is a larger deviation in the prediction with comprehensive axial wear coefficient(accuracy 41%, which is in agreement with the prediction of disc cutters' life in the field). This paper puts forth a new method concerning prediction of life span and wear of TBM disc cutters as well as timing for replacing disc cutters.

  15. Ash particle erosion on steam boiler convective section

    Energy Technology Data Exchange (ETDEWEB)

    Meuronen, V

    1998-12-31

    In this study, equations for the calculation of erosion wear caused by ash particles on convective heat exchanger tubes of steam boilers are presented. A new, three-dimensional test arrangement was used in the testing of the erosion wear of convective heat exchanger tubes of steam boilers. When using the sleeve-method, three different tube materials and three tube constructions could be tested. New results were obtained from the analyses. The main mechanisms of erosion wear phenomena and erosion wear as a function of collision conditions and material properties have been studied. Properties of fossil fuels have also been presented. When burning solid fuels, such as pulverized coal and peat in steam boilers, most of the ash is entrained by the flue gas in the furnace. In bubbling and circulating fluidized bed boilers, particle concentration in the flue gas is high because of bed material entrained in the flue gas. Hard particles, such as sharp edged quartz crystals, cause erosion wear when colliding on convective heat exchanger tubes and on the rear wall of the steam boiler. The most important ways to reduce erosion wear in steam boilers is to keep the velocity of the flue gas moderate and prevent channelling of the ash flow in a certain part of the cross section of the flue gas channel, especially near the back wall. One can do this by constructing the boiler with the following components. Screen plates can be used to make the velocity and ash flow distributions more even at the cross-section of the channel. Shield plates and plate type constructions in superheaters can also be used. Erosion testing was conducted with three types of tube constructions: a one tube row, an in- line tube bank with six tube rows, and a staggered tube bark with six tube rows. Three flow velocities and two particle concentrations were used in the tests, which were carried out at room temperature. Three particle materials were used: quartz, coal ash and peat ash particles. Mass loss

  16. Radioactive ion implantation as a tool for wear measurements

    International Nuclear Information System (INIS)

    Bagger, C.; Soerensen, G.

    1979-01-01

    The present paper deals with ion implantation of radioactive krypton ions in surfaces with aim of measuring wear of different magnetic materials in sound-heads. The technique is especially suited for a relatively fast comparison of wear-characteristics of materials of varying composition in small inaccessible areas. In the present case utilisation of a 60 KeV accelerator allows determination of a total wear as small as 0.05 μm with an accuracy of 10%. Further the technique yields information of the time dependence of the wear process with an accuracy less than 0.001 μm. (author)

  17. Erosive lichen planus: a therapeutic challenge.

    Science.gov (United States)

    Romero, Williams; Giesen, Laura; Navajas-Galimany, Lucas; Gonzalez, Sergio

    2016-01-01

    Erosive lichen planus is an uncommon variant of lichen planus. Chronic erosions of the soles, accompanied by intense and disabling pain, are some of its most characteristic manifestations. We present the case of a woman who developed oral and plantar erosive lichen planus associated with lichen planus pigmentosus and ungueal lichen planus that were diagnosed after several years. The patient failed to respond to multiple therapies requiring longstanding medication but remained refractory. Knowledge of the treatment options for erosive lichen planus is insufficient. Further research is required to clarify their effectiveness, ideally adopting an evidence-based methodology.

  18. Influence of contact conditions on vibration induced wear of metals

    International Nuclear Information System (INIS)

    Hofmann, P.J.; Schettler, T.; Wieling, N.; Steininger, D.A.

    1990-01-01

    Unfavourable design characteristics of nuclear power plant steam generators and heat exchangers in general may result in vibration induced tube wear. A systematic investigation was performed on the contact conditions which may appear between heat exchanger tubes and tube support structure and the influence of different parameters e.g., normal contact force, on the resulting steady state wear rates. It is concluded that not only are contact forces and sliding distances important in the wear process but also the type of relative motion has a decisive influence on the resulting wear rates. For a certain 'work rate', the wear rate caused by repeated impact motions between tube and tube support structure may be an order of magnitude higher than that caused by only sliding motion. This is the result of different operating wear mechanisms which are discussed in this paper. (orig.)

  19. Conception de couches minces tribologiques pour augmenter la resistance a l'erosion par impacts de particules

    Science.gov (United States)

    Hassani, Salim

    Solid particle erosion (SPE) is a serious problem in gas turbines, pumps, heat exchangers and piping systems in aircrafts and other applications. Sand and dust ingested by gas turbine engines may cause major damage to compressor gas path components, leading to severe performance degradation, excessive wear, increased maintenance and eventually premature failure of the engines. For the compressor section of aerospace gas turbine engines, in addition to the complex filtration systems used to screen the eroding particles, tribological coatings, such as TiN, Ti/TiN, CrN and TiAlN are used as protective layers of the base titanium alloy (Ti-6Al-4V) or stainless steels (17-4PH and 410) materials (substrates) against erosive wear. Such coatings can extend the service life of the components, but their performance still remains insufficient due to the complexity of failure mechanisms occurring upon SPE. Therefore, aerospace industry seeks to develop high performance coatings for the protection against erosion by solid particles. However, with many new materials used and tested for different applications and operation under different conditions, conducting experiments for each one of them is becoming increasingly difficult. Presently, coating selection criteria to prevent damage caused by erosion are based on trial and error experiments instead of prior design of coating's architecture and properties to maximize erosion resistance. The present work focuses on the use of advanced finite element (FE) methods to design erosion resistant (ER) coatings. It contributes a new methodology based on the analysis of transient stresses generated by a single impact event. Identification of coating architectures in which such stresses are minimized and crack propagation suppressed, allows one to predict and possibly minimize the erosion rate. Erosion mechanisms and governing erosion parameters are investigated to predict the coating behavior in simulated erosion conditions. The

  20. Leading edge erosion of coated wind turbine blades: Review of coating life models

    NARCIS (Netherlands)

    Slot, H.M.; Gelinck, E.R.M.; Rentrop, A.; van der Heide, Emile

    2015-01-01

    Erosion of the leading edge of wind turbine blades by droplet impingement wear, reduces blade aerodynamic efficiency and power output. Eventually, it compromises the integrity of blade surfaces. Elastomeric coatings are currently used for erosion resistance, yet the life of such coatings cannot be

  1. Influence of applied load on wear behavior of C/C-Cu composites under electric current

    Directory of Open Access Journals (Sweden)

    Jian Yin

    2017-04-01

    Full Text Available Using carbon fiber needled fabrics with Cu-mesh and graphite powder as the preform, Cu mesh modified carbon/carbon(C/C-Cu composites were prepared by chemical vapor deposition (CVD with C3H6 and impregnation-carbonization (I/C with furan resin. C/C composites, as a comparison, were also prepared. Their microstructures and wear morphologies were observed by optical microscopy (OM and scanning electron microscope (SEM, respectively. Wear behavior of C/C and C/C-Cu composites under different applied loads were investigated on a pin-on-disc wear tester. The results show that Cu meshes are well dispersed and pyrolytic carbon is in rough laminar structure. Both C/C and C/C-Cu composites had good wear properties. The current-carrying capacity of C/C-Cu composites increases and the arc discharge is hindered as the applied load increases from 40 N to 80 N. Both C/C and C/C-Cu composites had good wear properties. The mass wear rate of C/C-Cu composites under 80 N was only 4.2% of that under 60 N. In addition, C/C-Cu composites represent different wear behaviors because wear mechanisms of arc erosion, abrasive wear, adhesive wear, and oxidative wear are changing under different applied loads.

  2. Optical wear monitoring

    Science.gov (United States)

    Kidane, Getnet S; Desilva, Upul P.; He, Chengli; Ulerich, Nancy H.

    2016-07-26

    A gas turbine includes first and second parts having outer surfaces located adjacent to each other to create an interface where wear occurs. A wear probe is provided for monitoring wear of the outer surface of the first part, and includes an optical guide having first and second ends, wherein the first end is configured to be located flush with the outer surface of the first part. A fiber bundle includes first and second ends, the first end being located proximate to the second end of the optical guide. The fiber bundle includes a transmit fiber bundle comprising a first plurality of optical fibers coupled to a light source, and a receive fiber bundle coupled to a light detector and configured to detect reflected light. A processor is configured to determine a length of the optical guide based on the detected reflected light.

  3. Erosion-Oxidation Response of Boiler Grade Steels: A Mathematical Investigation

    Directory of Open Access Journals (Sweden)

    S. K. Das

    2008-01-01

    Full Text Available A ductile erosion model embodying the mechanisms of erosion involving cutting wear and repeated plastic deformation has been developed to predict erosion rates of boiler grade steels. The issue of erosion-oxidation interaction has also been addressed to further predict the mass loss resulted from this composite mechanism. A deterministic formalism for the kinetics of oxide-scale growth and a probabilistic approach to characterize the material loss are employed to describe simultaneous actions of high-temperature oxidation and mechanical erosion. The model predictions are in good agreement with the published data.

  4. Erosion-corrosion of structural materials of wet steam turbines

    International Nuclear Information System (INIS)

    Tomarov, G.V.

    1989-01-01

    A model of erosion-corrosion wear of elements of a wet steam zone and a condensate-feeding path of turbines is considered. It is shown that diffusion of impurities and corrosion products in pores of an oxide layer is the control mechanism under conditions of laminar flow of a media. Processes of mass transfer are controlling factors in turbulent flow

  5. Ways of TPP and NPP powerful steam turbine blade erosion decreasing in low flow rate regimes

    International Nuclear Information System (INIS)

    Khrabrov, P.V.; Khaimov, V.A.; Matveenko, V.A.

    1986-01-01

    A systematized approach to the problem of efficient cooling of flow passage and exhaust parts of TPP and NPP steam turbines and prevention of erosion wear of inlet and outlet edges of operating blades is presented. Methods for LP casing cooling and sources of erosion-hazard moisture as well as the main technological and design measures to decrease the erosion of blades are determined

  6. Rainfall Erosivity in Europe

    DEFF Research Database (Denmark)

    Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale

    2015-01-01

    Rainfall is one the main drivers of soil erosion. The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the Rfactor in the USLE model and its revised version, RUSLE. At national...... and continental levels, the scarce availability of data obliges soil erosion modellers to estimate this factor based on rainfall data with only low temporal resolution (daily, monthly, annual averages). The purpose of this study is to assess rainfall erosivity in Europe in the form of the RUSLE R-factor, based...

  7. CFD study of fluid flow changes with erosion

    Science.gov (United States)

    López, Alejandro; Stickland, Matthew T.; Dempster, William M.

    2018-06-01

    For the first time, a three dimensional mesh deformation algorithm is used to assess fluid flow changes with erosion. The validation case chosen is the Jet Impingement Test, which was thoroughly analysed in previous works by Hattori et al. (Kenichi Sugiyama and Harada, 2008), Gnanavelu et al. in (Gnanavelu et al., 2009, 2011), Lopez et al. in (Lopez et al., 2015) and Mackenzie et al. in (Mackenzie et al., 2015). Nguyen et al. (2014) showed the formation of a new stagnation area when the wear scar is deep enough by performing a three-dimensional scan of the wear scar after 30 min of jet impingement test. However, in the work developed here, this stagnation area was obtained solely by computational means. The procedure consisted of applying an erosion model in order to obtain a deformed geometry, which, due to the changes in the flow pattern lead to the formation of a new stagnation area. The results as well as the wear scar were compared to the results by Nguyen et al. (2014) showing the same trend. OpenFOAM® was the software chosen for the implementation of the deforming mesh algorithm as well as remeshing of the computational domain after deformation. Different techniques for mesh deformation and approaches to erosion modelling are discussed and a new methodology for erosion calculation including mesh deformation is developed. This new approach is independent of the erosion modelling approach, being applicable to both Eulerian and Lagrangian based equations for erosion calculation. Its different applications such as performance decay in machinery subjected to erosion as well as modelling of natural erosion processes are discussed here.

  8. Assessment of fretting wear in Hanaro fuel

    International Nuclear Information System (INIS)

    Chae, Hee Taek; Lim, Kyeong Hwan; Kim, Hark Rho

    1999-06-01

    Since the first fuel loading on Feb. 1995, various zero-power tests were performed in HANARO and power ascending tests followed. After the initial fuel loading, Hanaro operation staffs inspected only two fuel bundles which were evaluated to have the highest power at the end of each cycle and they did not recognize anything peculiar in the inspected bundles. At the end of 1996, Hanaro staffs found severe wear damages in the fuel components. After that, the 4th cycle core was re-arranged with fresh fuels only to investigate wear phenomena on the fuel components. The fuel inspections have been performed 25 times periodically since the core re-configuration. In this report, fretting wear characteristics of the fuel assemblies were evaluated and summarized. Wear damages of the improved fuel assembly to resolve the wear problem were compared with those of the original fuel assembly. Based on the results of the fuel inspections, we suggest that fuel inspection need not be done for the first 60 pump operation days in order to reduce the potential of damage by a fuel handling error and an operator's burden of the fuel inspection. (author). 6 refs., 10 tabs., 5 figs

  9. Wear-Out Sensitivity Analysis Project Abstract

    Science.gov (United States)

    Harris, Adam

    2015-01-01

    During the course of the Summer 2015 internship session, I worked in the Reliability and Maintainability group of the ISS Safety and Mission Assurance department. My project was a statistical analysis of how sensitive ORU's (Orbital Replacement Units) are to a reliability parameter called the wear-out characteristic. The intended goal of this was to determine a worst case scenario of how many spares would be needed if multiple systems started exhibiting wear-out characteristics simultaneously. The goal was also to determine which parts would be most likely to do so. In order to do this, my duties were to take historical data of operational times and failure times of these ORU's and use them to build predictive models of failure using probability distribution functions, mainly the Weibull distribution. Then, I ran Monte Carlo Simulations to see how an entire population of these components would perform. From here, my final duty was to vary the wear-out characteristic from the intrinsic value, to extremely high wear-out values and determine how much the probability of sufficiency of the population would shift. This was done for around 30 different ORU populations on board the ISS.

  10. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro; Ruggeri, Fabrizio; Tempone, Raul; Vilanova, Pedro

    2014-01-01

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict

  11. Wear Behavior of an Unstable Knee: Stabilization via Implant Design?

    Directory of Open Access Journals (Sweden)

    Jörn Reinders

    2014-01-01

    Full Text Available Background. Wear-related failures and instabilities are frequent failure mechanisms of total knee replacements. High-conforming designs may provide additional stability for the joint. This study analyzes the effects of a ligamentous insufficiency on the stability and the wear behavior of a high-conforming knee design. Methods. Two simulator wear tests were performed on a high-conforming total knee replacement design. In the first, a ligamentous-stable knee replacement with a sacrificed anterior cruciate ligament was simulated. In the second, a ligamentous-unstable knee with additionally insufficient posterior cruciate ligament and medial collateral ligament was simulated. Wear was determined gravimetrically and wear particles were analyzed. Implant kinematics was recorded during simulation. Results. Significantly higher wear rates (P≤0.001 were observed for the unstable knee (14.58±0.56 mg/106 cycles compared to the stable knee (7.97 ± 0.87 mg/106 cycles. A higher number of wear particles with only small differences in wear particle characteristics were observed. Under unstable knee conditions, kinematics increased significantly for translations and rotations (P≤0.01. This increase was mainly attributed to higher tibial posterior translation and internal rotations. Conclusion. Higher kinematics under unstable test conditions is a result of insufficient stabilization via implant design. Due to the higher kinematics, increased wear was observed in this study.

  12. Potential countersample materials for in vitro simulation wear testing.

    Science.gov (United States)

    Shortall, Adrian C; Hu, Xiao Q; Marquis, Peter M

    2002-05-01

    Any laboratory investigation of the wear resistance of dental materials needs to consider oral conditions so that in vitro wear results can be correlated with in vivo findings. The choice of the countersample is a critical factor in establishing the pattern of tribological wear and in achieving an efficient in vitro wear testing system. This research investigated the wear behavior and surface characteristics associated with three candidate countersample materials used for in vitro wear testing in order to identify a possible suitable substitute for human dental enamel. Three candidate materials, stainless steel, steatite and dental porcelain were evaluated and compared to human enamel. A variety of factors including hardness, wear surface evolution and frictional coefficients were considered, relative to the tribology of the in vivo situation. The results suggested that the dental porcelain investigated bore the closest similarity to human enamel of the materials investigated. Assessment of potential countersample materials should be based on the essential tribological simulation supported by investigations of mechanical, chemical and structural properties. The selected dental porcelain had the best simulating ability among the three selected countersample materials and this class of material may be considered as a possible countersample material for in vitro wear test purposes. Further studies are required, employing a wider range of dental ceramics, in order to optimise the choice of countersample material for standardized in vitro wear testing.

  13. The synergism of impact wear and oxidation in carbon dioxide environments

    International Nuclear Information System (INIS)

    Morri, J.R.

    1987-01-01

    The impact fretting wear characteristics in Co 2 of a 9%Cr steel against a 310SS counterface have been studied between 100 0 and 500 0 C. An energy effect was identified in which high energy impacts suppressed a severe-to-mild wear transition for low energy impacts between 250 0 and 350 0 C. In addition a severe form of high temperature wear (above 400 0 C) was observed in which pitting of the 9Cr steel and transfer to the 310SS occurred. Subsequent wear scar examination revealed a wear mechanism dominated by the interaction of the oxidation characteristics and the changing mechanical behaviour of the 9Cr. (author)

  14. Mapping erosion from space

    NARCIS (Netherlands)

    Vrieling, A.

    2007-01-01

    Soil erosion by water is the most important land degradation problem worldwide. Spatial information on erosion is required for defining effective soil and water conservation strategies. Satellite remote sensing can provide relevant input to regional erosion assessment. This thesis comprises a review

  15. Erosion-corrosion

    International Nuclear Information System (INIS)

    Aghili, B.

    1999-05-01

    A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment

  16. Assessing storm erosion hazards

    NARCIS (Netherlands)

    Ranasinghe, Ranasinghe W M R J B; Callaghan, D.; Ciavola, Paolo; Coco, Giovanni

    2017-01-01

    The storm erosion hazard on coasts is usually expressed as an erosion volume and/or associated episodic coastline retreat. The accurate assessment of present-day and future storm erosion volumes is a key task for coastal zone managers, planners and engineers. There are four main approaches that can

  17. Slurry Erosion Studies on Surface Modified 13Cr-4Ni Steels: Effect of Angle of Impingement and Particle Size

    Science.gov (United States)

    Manisekaran, T.; Kamaraj, M.; Sharrif, S. M.; Joshi, S. V.

    2007-10-01

    Hydroturbine steels, such as 13Cr-4Ni martensitic steels, are generally subjected to heavy-erosive wear and loss of efficiency due to solid particulate entrainment in the water. Surface-modified steels have proven to give better performance in terms of erosive wear resistance. In the present study, an attempt is made to investigate the effect of angle of impingement and particle size on slurry-jet erosion behavior of pulsed plasma nitrided and laser hardened 13Cr-4Ni steels. Laser hardening process has shown good performance at all angles of impingement due to martensitic transformation of retained austenite. Plastic deformation mode of material removal was also an evident feature of all laser-hardened surface damage locations. However, pulsed-plasma nitrided steels have exhibited chip formation and micro-cutting mode of erosive wear. Erosion with 150-300 μm size was twice compared to 150 μm size slurry particulates.

  18. Corrosive wear. Evaluation of wear and corrosive resistant materials; Noetningskorrosion. Utvaerdering av noetnings- och korrosionsbestaendiga material

    Energy Technology Data Exchange (ETDEWEB)

    Persson, H.; Hjertsen, D.; Waara, P.; Prakash, B.; Hardell, J.

    2007-12-15

    assumption that a 60% reduction of the thickness is acceptable. The changes of the operation conditions, particularly the lower rotating speed that the new design led to, have shifted the wear/corrosion condition so that corrosion is more dominating in the wear-corrosion. This is obvious as the SS2377, one of the softest of the evaluated materials, shows low wear rate due to its good corrosion resistant characteristics. The design of the screw has proved to be very crucial for wear-corrosion. The results from the wear-corrosion test show a number of effects that are more or less difficult to explain. One example is that the SS2377 have better wear resistance than the harder materials in both corrosion and in non-corrosive environment. The general conclusion from these testing is that the conditions at the screw have not been successfully imitated. For the prediction of the useful life, a wear-corrosion model has been developed to be used with operation data to follow and/or predict the wear-corrosion. Especially with SS2377, where the synergy effects between corrosion and abrasion is small, a good conformance can be reached. The model needs however further verification to become more general

  19. Millisecond bearing wear

    International Nuclear Information System (INIS)

    Blatchley, C.; Sioshansi, P.

    1987-01-01

    Radionuclides have been widely used for many purposes in medicine, metals, transportation, manufacturing and research. Approximately 200 artificially produced nuclides are commercially available from reactors or accelerator sources. Another 400 or so have properties which may make them useful if satisfactory methods of production can be developed. One of the most economically important industrial applications of radionuclides has been in wear measurement and condition monitoring in reciprocating engines. The general techniques developed for this purpose have also been applied in a number of other areas besides engine or lubrication studies. The wear of floor wax applied to linoleum, for example, has been measured by mixing shortlived radionuclides in the wax. In those applications where the material is tagged and then followed, the radionuclides are termed ''tracers,'' similar to the medical tracer materials used to measure uptake or metabolism of biologically active chemicals in the body. The alternate function for the radionuclides is to act as ''markers'' which indicate the amount of material which is remaining at the location of the original activation. Both approaches require that the debris removed from the surface must be carried away from the original site. The first application of radioactive tracers as a diagnostic tool in engines was in 1949. In this technique, an entire wearing part such as a piston ring or gear was first exposed to neutrons in a nuclear reactor. This caused the entire volume of the part to become radioactive. The part was next installed and exposed to wear in the operating engine. Detectors placed near the oil line, an oil filter or a sediment trap then determined the amount of debris from the part by counting the gamma rays escaping from the debris

  20. Erosion testing of hard materials and coatings

    Energy Technology Data Exchange (ETDEWEB)

    Hawk, Jeffrey A.

    2005-04-29

    Erosion is the process by which unconstrained particles, usually hard, impact a surface, creating damage that leads to material removal and component failure. These particles are usually very small and entrained in fluid of some type, typically air. The damage that occurs as a result of erosion depends on the size of the particles, their physical characteristics, the velocity of the particle/fluid stream, and their angle of impact on the surface of interest. This talk will discuss the basics of jet erosion testing of hard materials, composites and coatings. The standard test methods will be discussed as well as alternative approaches to determining the erosion rate of materials. The damage that occurs will be characterized in genera1 terms, and examples will be presented for the erosion behavior of hard materials and coatings (both thick and thin).

  1. Dental Erosion and Caries Status of Chinese University Students.

    Science.gov (United States)

    Chu, Chun Hung; Ng, Alice; Chau, Alex Man Him; Lo, Edward Chin Man

    2015-01-01

    To describe the prevalence and severity of dental erosion and caries experience of Chinese university students in Hong Kong. First-year Chinese students were invited to attend a dental clinic at a university campus in Hong Kong during their freshman orientation. A questionnaire was used to investigate the potential factors affecting their dental status, including sociodemographic factors, toothbrushing habits, dietary habits (consumption of sugary drinks), time elapsed since last dental check-up and self-perceived dental erosion status. Three calibrated dentists performed the clinical examinations. Dental erosion was evaluated using the modified Basic Erosive Wear Examination (BEWE) and dental caries experience was measured using the DMFT index. In total, 600 participants aged 18-21 were examined and 44% showed some signs of dental erosion (maximum BEWE > 0). Severe dental erosion (BEWE = 3) was found in 1% of the adults. Many (69%) had caries experience (DMFT > 0); their mean DMFT score was 2.5 ± 2.7 (± SD). The total BEWE scores were found to be associated with age and self-perception of tooth misalignment. No correlation was found between BEWE score and dietary habits, oral hygiene practices or self-perceived dental erosion status. Females, those whose last dental check-up was more than a year ago and those who perceived having dental decay or tooth wear had higher caries experience. Nearly half of the Chinese Hong Kong university students had signs of dental erosion, but very few showed signs of severe erosion. Caries experience was widespread but not high.

  2. Managing dental erosion.

    Science.gov (United States)

    Curtis, Donald A; Jayanetti, Jay; Chu, Raymond; Staninec, Michal

    2012-01-01

    The clinical signs of dental erosion are initially subtle, yet often progress because the patient remains asymptomatic, unaware and uninformed. Erosion typically works synergistically with abrasion and attrition to cause loss of tooth structure, making diagnosis and management complex. The purpose of this article is to outline clinical examples of patients with dental erosion that highlight the strategy of early identification, patient education and conservative restorative management. Dental erosion is defined as the pathologic chronic loss of dental hard tissues as a result of the chemical influence of exogenous or endogenous acids without bacterial involvement. Like caries or periodontal disease, erosion has a multifactorial etiology and requires a thorough history and examination for diagnosis. It also requires patient understanding and compliance for improved outcomes. Erosion can affect the loss of tooth structure in isolation of other cofactors, but most often works in synergy with abrasion and attrition in the loss of tooth structure (Table 1). Although erosion is thought to be an underlying etiology of dentin sensitivity, erosion and loss of tooth structure often occurs with few symptoms. The purpose of this article is threefold: first, to outline existing barriers that may limit early management of dental erosion. Second, to review the clinical assessment required to establish a diagnosis of erosion. And third, to outline clinical examples that review options to restore lost tooth structure. The authors have included illustrations they hope will be used to improve patient understanding and motivation in the early management of dental erosion.

  3. Monthly Rainfall Erosivity Assessment for Switzerland

    Science.gov (United States)

    Schmidt, Simon; Meusburger, Katrin; Alewell, Christine

    2016-04-01

    Water erosion is crucially controlled by rainfall erosivity, which is quantified out of the kinetic energy of raindrop impact and associated surface runoff. Rainfall erosivity is often expressed as the R-factor in soil erosion risk models like the Universal Soil Loss Equation (USLE) and its revised version (RUSLE). Just like precipitation, the rainfall erosivity of Switzerland has a characteristic seasonal dynamic throughout the year. This inter-annual variability is to be assessed by a monthly and seasonal modelling approach. We used a network of 86 precipitation gauging stations with a 10-minute temporal resolution to calculate long-term average monthly R-factors. Stepwise regression and Monte Carlo Cross Validation (MCCV) was used to select spatial covariates to explain the spatial pattern of R-factor for each month across Switzerland. The regionalized monthly R-factor is mapped by its individual regression equation and the ordinary kriging interpolation of its residuals (Regression-Kriging). As covariates, a variety of precipitation indicator data has been included like snow height, a combination of hourly gauging measurements and radar observations (CombiPrecip), mean monthly alpine precipitation (EURO4M-APGD) and monthly precipitation sums (Rhires). Topographic parameters were also significant explanatory variables for single months. The comparison of all 12 monthly rainfall erosivity maps showed seasonality with highest rainfall erosivity in summer (June, July, and August) and lowest rainfall erosivity in winter months. Besides the inter-annual temporal regime, a seasonal spatial variability was detectable. Spatial maps of monthly rainfall erosivity are presented for the first time for Switzerland. The assessment of the spatial and temporal dynamic behaviour of the R-factor is valuable for the identification of more susceptible seasons and regions as well as for the application of selective erosion control measures. A combination with monthly vegetation

  4. Influence of dissolution media pH and USP1 basket speed on erosion and disintegration characteristics of immediate release metformin hydrochloride tablets.

    Science.gov (United States)

    Desai, Divyakant; Wong, Benjamin; Huang, Yande; Tang, Dan; Hemenway, Jeffrey; Paruchuri, Srinivasa; Guo, Hang; Hsieh, Daniel; Timmins, Peter

    2015-01-01

    To investigate the influence of the pH of the dissolution medium on immediate release 850 mg metformin hydrochloride tablets. A traditional wet granulation method was used to manufacture metformin hydrochloride tablets with or without a disintegrant. Tablet dissolution was conducted using the USP apparatus I at 100 rpm. In spite of its pH-independent high solubility, metformin hydrochloride tablets dissolved significantly slower in 0.1 N HCl (pH 1.2) and 50 mM pH 4.5 acetate buffer compared with 50 mM pH 6.8 phosphate buffer, the dissolution medium in the USP. Metformin hydrochloride API compressed into a round 1200 mg disk showed a similar trend. When basket rotation speed was increased from 100 to 250 rpm, the dissolution of metformin hydrochloride tablets was similar in all three media. Incorporation of 2% w/w crospovidone in the tablet formulation improved the dissolution although the pH-dependent trend was still evident, but incorporation of 2% w/w croscarmellose sodium resulted in rapid pH-independent tablet dissolution. In absence of a disintegrant in the tablet formulation, the dissolution was governed by the erosion-diffusion process. Even for a highly soluble drug, a super-disintegrant was needed in the formulation to overcome the diffusion layer limitation and change the dissolution mechanism from erosion-diffusion to disintegration.

  5. Bedrock river erosion measurements and modelling along a river of the Frontal Himalaya

    Science.gov (United States)

    Lave, Jerome; Dubille, Matthieu

    2017-04-01

    River incision is a key process in mountains denudation and therefore in landscape evolution models. Despite its importance, most incision models for mountain rivers rely on simplified, or quite empirical relations, and generally only consider annual average values for water discharge and sediment flux. In contrast, very few studies consider mechanistic models at the timescale of a flood, and try to bridge the gap between experimental or theoretical approaches and long term river incision studies. In this contribution, we present observations made during 7 monsoon seasons on fluvial bedrock erosion along the Bakeya river across the Frontal Himalaya in Central Nepal. Along its lower gorge, this river incises alternation of indurated sandstone and less resistant claystone, at Holocene rates larger than 10mm/yr. More importantly, its upper drainage mostly drains through non-cohesive conglomerate which allows, in this specific setting, estimating the bedload characteristics and instantaneous fluxes, i.e. a pre-requisite to test mechanistic models of fluvial erosion. During the study period, we monitored and documented the channel bank erosion in order to understand the amplitude of the erosion processes, their occurrence in relation with hydrology, in order to test time-integrated models of erosion. Besides hydrologic monitoring, erosion measurements were threefold: (1) at the scale of the whole monsoon, plucking and block removal by repeated photo surveys of a 400m long channel reach, (2) detailed microtopographic surveys of channel bedrock elevation along a few sandstone bars to document their abrasion, (3) real time measurement of fluvial bedrock wear to document erosion timing using a new erosion sensor. Results indicate that: 1. Erosion is highly dependent on rock resistance, but on average block detachment and removal is a more efficient process than bedrock attrition, and operates at a rate that permit channel banks downcutting to keep pace with Holocene uplift

  6. Combating Wear of ASTM A36 Steel by Surface Modification Using Thermally Sprayed Cermet Coatings

    OpenAIRE

    Shibe, Vineet; Chawla, Vikas

    2016-01-01

    Thermal spray coatings can be applied economically on machine parts to enhance their requisite surface properties like wear, corrosion, erosion resistance, and so forth. Detonation gun (D-Gun) thermal spray coatings can be applied on the surface of carbon steels to improve their wear resistance. In the present study, alloy powder cermet coatings WC-12% Co and Cr3C2-25% NiCr have been deposited on ASTM A36 steel with D-Gun thermal spray technique. Sliding wear behavior of uncoated ASTM A36 ste...

  7. Impact of metal matrix composite on the evolution and erosion performance characteristics of non lubricated-dry abrasive degradation of ternary composite coating for refineries system

    Science.gov (United States)

    Anawe, Paul Apeye Lucky; Fayomi, Ojo Sunday Isaac

    2018-06-01

    The application of rational design principles and process in electrodeposition can eliminate many engineering catastrophes related to corrosion and micromechanical failure in service. This has led to appreciate the need of surface modification on component for enhance life span. Admixed Zn-30Al-13Ti-chloride composite bath was electrolytically prepared and successfully deposited on UNS G10150 mild steel substrate by zinc dual anode deposition processes within an interval of applied current density, particle concentration and constant time. The codeposition of Zn-Al-Ti coating was studied in the presence of other bath ingredient. The effect of deposition current and particle concentration on structural property, adhesion behaviour, ideal crystal orientation, surface topography and electrochemical properties of Zn-Al-Ti alloy coating series on mild steel were analytically examined. The wear stability of the developed composite materials was examined via sliding reciprocating rig. The structural integrity was examined with scanning electron microscope equipped with EDS, X-ray diffraction; Atomic force microscope, dura scan micro-hardness tester and 3 μ metrohm Potentiostat/galvanostat. Interestingly the induced activity of the Zn-Al-Ti chloride composite alloy results into excellent structural modification and stable crystal precipitation within the structural interface as a result of Zn3Al, Zn2Ti and ZnAl3Ti2 intermetallic phase. The obtained results showed that the introduction of Ti particles in the presence of other bath additive in the plating bath mostly modified the surface and brings an increase in the microhardness, corrosion resistance and reduce wear deformation of Zn-Al-Ti chloride composite alloy.

  8. Fretting Wear Behaviors of Aluminum Cable Steel Reinforced (ACSR Conductors in High-Voltage Transmission Line

    Directory of Open Access Journals (Sweden)

    Xingchi Ma

    2017-09-01

    Full Text Available This work reports the fretting wear behavior of aluminum cable steel reinforced (ACSR conductors for use in high-voltage transmission line. Fretting wear tests of Al wires were conducted on a servo-controlled fatigue testing machine with self-made assistant apparatus, and their fretting process characteristics, friction force, wear damage, and wear surface morphology were detailed analyzed. The results show that the running regime of Al wires changes from a gross slip regime to a mixed regime more quickly as increasing contact load. With increasing amplitudes, gross slip regimes are more dominant under contact loads of lower than 30 N. The maximum friction force is relatively smaller in the NaCl solution than in a dry friction environment. The primary wear mechanisms in dry friction environments are abrasive wear and adhesive wear whereas abrasive wear and fatigue damage are dominant in NaCl solution.

  9. Wear of human enamel: a quantitative in vitro assessment.

    Science.gov (United States)

    Kaidonis, J A; Richards, L C; Townsend, G C; Tansley, G D

    1998-12-01

    Many factors influence the extent and rate at which enamel wears. Clinical studies in humans are limited by difficulties in the accurate quantification of intra-oral wear and by a lack of control over the oral environment. The purpose of this study was to determine the wear characteristics of human dental enamel under controlled experimental conditions. An electro-mechanical tooth wear machine, in which opposing enamel surfaces of sectioned, extracted teeth were worn under various conditions, was used to simulate tooth grinding or bruxism. Enamel surface wear was quantified by weight to an accuracy of 0.1 mg, with water uptake and loss controlled. The variables considered included the structure and hardness of enamel, facet area, duration of tooth contact, relative speed of opposing surfaces, temperature, load, pH, and the nature of the lubricant. Enamel wear under non-lubricated conditions increased with increasing load over the range of 1.7 to 16.2 kg. The addition of a liquid lubricant (pH = 7) reduced enamel wear up to 6.7 kg, but when the load increased above this threshold, the rate of wear increased dramatically. With the viscosity of the lubricant constant and pH = 3, the rate of wear was further reduced to less than 10% of the non-lubricated rate at 9.95 kg, after which the rate again increased substantially. Under more extreme conditions (pH = 1.2, simulating gastric acids), the wear was excessive under all experimental loads. When saliva was used as a lubricant, the amount of wear was relatively low at 9.95 kg, but rapid wear occurred at 14.2 kg and above. These results indicate that under non-lubricated conditions, enamel wear remains low at high loads due to the dry-lubricating capabilities of fine enamel powder. Under lubricated conditions, low loads with an acidic lubricant lead to little enamel wear, whereas very low pH results in a high rate of wear under all loads.

  10. Assessment of Tooth Wear Among Glass Factory Workers: WHO 2013 Oral Health Survey.

    Science.gov (United States)

    Chaturvedi, Pulkit; Bhat, Nagesh; Asawa, Kailash; Tak, Mridula; Bapat, Salil; Gupta, Vivek Vardhan

    2015-08-01

    Glass factory workers are often exposed to the hazardous environment that leads to deleterious oral health and subsequently, general health. We planned to determine the effects of the particulates present in the milieu on the tooth wear among workers. To assess tooth wear among glass factory workers in Jaipur, Rajasthan, India. A descriptive cross-sectional survey was conducted among 936 glass workers in Jaipur, Rajasthan, India from January-June 2014. A survey proforma was designed for tooth wear evaluation with the help of WHO Oral Health Assessment form 2013 (for adults). Information regarding oral health practices, adverse habits and dietary habits, demographic details was gathered and clinical parameters were recorded. The Chi-square test, t-test, One-way Analysis of Variance and a Stepwise multiple linear regression analysis. The most prevalent form of erosion was enamel erosion (589, 62.93%) with few subjects of deeper dentinal erosion and the difference was statistically significant (p=0.001). Dental erosion was found to be higher among males compared to females. Years of experience and educational status were identified as best predictors for dental erosion. It was concluded that there was considerable evidence of dental erosion found among the factory workers. Due to ignorance on social, cultural and health aspects, professional approach with regular dental care services for detection of early symptoms and planning of preventive strategies is warranted.

  11. Investigation of machining damage and tool wear resulting from drilling powder metal aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Fell, H.A. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States)

    1997-05-01

    This report documents the cutting of aluminum powder metallurgy (PM) parts for the North Carolina Manufacturing Extension Partnership. The parts, an aluminum powder metal formulation, were supplied by Sinter Metals Inc., of Conover, North Carolina. The intended use of the alloy is for automotive components. Machining tests were conducted at Y-12 in the machine shop of the Skills Demonstration Center in Building 9737. Testing was done on June 2 and June 3, 1997. The powder metal alloy tested is very abrasive and tends to wear craters and produce erosion effects on the chip washed face of the drills used. It also resulted in huge amounts of flank wear and degraded performance on the part of most drills. Anti-wear coatings on drills seemed to have an effect. Drills with the coating showed less wear for the same amount of cutting. The usefulness of coolants and lubricants in reducing tool wear and chipping/breakout was not investigated.

  12. Effect of carbonated beverages, coffee, sports and high energy drinks, and bottled water on the in vitro erosion characteristics of dental enamel.

    Science.gov (United States)

    Kitchens, Michael; Owens, Barry M

    2007-01-01

    This study evaluated the effect of carbonated and non-carbonated beverages, bottled and tap water, on the erosive potential of dental enamel with and without fluoride varnish protection. Beverages used in this study included: Coca Cola Classic, Diet Coke, Gatorade sports drink, Red Bull high-energy drink, Starbucks Frappuccino coffee drink, Dasani water (bottled), and tap water (control). Enamel surfaces were coated with Cavity Shield 5% sodium fluoride treatment varnish. Twenty-eight previously extracted human posterior teeth free of hypocalcification and caries were used in this study. The coronal portion of each tooth was removed and then sectioned transverse from the buccal to lingual surface using a diamond coated saw blade. The crown sections were embedded in acrylic resin blocks leaving the enamel surfaces exposed. The enamel surfaces were polished using 600 to 2000 grit abrasive paper and diamond paste. Test specimens were randomly distributed to seven beverage groups and comprised 4 specimens per group. Two specimens per beverage group were treated with a fluoride varnish while 2 specimens did not receive fluoride coating. Surface roughness (profilometer) readings were performed at baseline (prior to fluoride treatment and immersion in the beverage) and again, following immersion for 14 days (24 hours/day). The test beverages were changed daily and the enamel specimens were immersed at 37 degrees C. Surface roughness data was evaluated using multiple factor ANOVA at a significance level of pStarBucks coffee, Dasani water, and tap water. Fluoride varnish was not a significant impact factor; however, beverage (type) and exposure time were significant impact variables. Both carbonated and non-carbonated beverages displayed a significant erosive effect on dental enamel; however, fluoride varnish treatments did not demonstrate a significant protective influence on enamel surfaces.

  13. MOCEAN SURF WEAR -MALLISTO

    OpenAIRE

    Lehtovaara, Hanna

    2013-01-01

    Surffi on urheilulaji, jossa kuljetaan aallon päällä surffilaudalla. Surffaus on lähtöisin Polynesiasta, mutta nykypäivänä surffausta harrastetaan ympäri maailmaa. Opinnäytetyö käsittelee surf wear -malliston suunnittelua ja toteuttamista omalle toi-minimelle Mocean. Työn tavoitteena oli suunnitella toimiva, mutta myös trendikäs mallisto naissurffareille. Mallisto sisältää bikineitä, surffipaitoja legginsejä ja shortseja. Mallisto on suunniteltu naissurffareille, jotka surffaavat lämpimis...

  14. Wear Particle Atlas. Revised

    Science.gov (United States)

    1982-06-28

    Superintendent NOTICE Reproduction of this document in any form by other than naval activities is/Jotbvlhorized except isys^iedcil approval of the SecretarWof...constant. •.■, -1 "if -w \\ SÄNPLlWi V» IVf Figure 3.1.1.1 Simplified Oil Path Ref 21 Scott. D, McCullagh. PJ and Campbell GW Condition Monitoring...Wear Particles in Human Synovial Fluid Arthritis and Rheumatism, 24 (1981) 912-918 30 Evans. C H .andTew W P isolationof Biological Materials

  15. Lubricity Additives and Wear with DME in Diesel Injection Pumps

    DEFF Research Database (Denmark)

    Nielsen, Kasper; Sorenson, Spencer C.

    1999-01-01

    In recent years it has been demonstrated that Dimethyl Ether (DME) possess many characteristics that could make it a successful alternative to diesel in the next century. High wear of the fuel injection system has been reported. This is caused by lack of natural protective constituents of Dimethyl...... wear of standard diesel jerk pump plungers elements were made with weight measurements, diameter measurements, 2-D and 3-D surface roughness measurements, and photography by a Michelson interferometer. Several lubricity additives were tested, but none reduced wear levels to those for diesel fuel...

  16. Hardfacing materials used in valves for seating and wear surfaces

    International Nuclear Information System (INIS)

    Knecht, W.G.

    1996-01-01

    Most valves and essentially all critical service valves utilize hardfacing materials for seating and wear surfaces to minimize wear and galling. The type of hardfacing materials used, the methods of deposition, and the quality of the final product all contribute to the wear characteristics, required operating force, and life of the final product. Over the last forty years the most prevalent hardfacing materials furnished to the commercial nuclear industry consisted of cobalt base and nickel base materials. In the last several years there has been extensive development and evaluation work performed on iron base hardfacing materials. This presentation will address the wear characteristics of the various materials and the importance of consistent quality of deposited materials necessary to achieve optimum product performance and longevity

  17. Hardfacing materials used in valves for seating and wear surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Knecht, W.G.

    1996-12-01

    Most valves and essentially all critical service valves utilize hardfacing materials for seating and wear surfaces to minimize wear and galling. The type of hardfacing materials used, the methods of deposition, and the quality of the final product all contribute to the wear characteristics, required operating force, and life of the final product. Over the last forty years the most prevalent hardfacing materials furnished to the commercial nuclear industry consisted of cobalt base and nickel base materials. In the last several years there has been extensive development and evaluation work performed on iron base hardfacing materials. This presentation will address the wear characteristics of the various materials and the importance of consistent quality of deposited materials necessary to achieve optimum product performance and longevity.

  18. Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Cook, B. A.; Harringa, J. L.; Russel, A. M.

    2012-12-01

    This report summarizes the work performed by an Ames-led project team under a 4-year DOE-ITP sponsored project titled, 'Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency.' The Report serves as the project deliverable for the CPS agreement number 15015. The purpose of this project was to develop and commercialize a family of lightweight, bulk composite materials that are highly resistant to degradation by erosive and abrasive wear. These materials, based on AlMgB{sub 14}, are projected to save over 30 TBtu of energy per year when fully implemented in industrial applications, with the associated environmental benefits of eliminating the burning of 1.5 M tons/yr of coal and averting the release of 4.2 M tons/yr of CO{sub 2} into the air. This program targeted applications in the mining, drilling, machining, and dry erosion applications as key platforms for initial commercialization, which includes some of the most severe wear conditions in industry. Production-scale manufacturing of this technology has begun through a start-up company, NewTech Ceramics (NTC). This project included providing technical support to NTC in order to facilitate cost-effective mass production of the wear-resistant boride components. Resolution of issues related to processing scale-up, reduction in energy intensity during processing, and improving the quality and performance of the composites, without adding to the cost of processing were among the primary technical focus areas of this program. Compositional refinements were also investigated in order to achieve the maximum wear resistance. In addition, synthesis of large-scale, single-phase AlMgB{sub 14} powder was conducted for use as PVD sputtering targets for nanocoating applications.

  19. Wear of polymers and composites

    CERN Document Server

    Abdelbary, Ahmed

    2015-01-01

    In the field of tribology, the wear behaviour of polymers and composite materials is considered a highly non-linear phenomenon. Wear of Polymers and Composites introduces fundamentals of polymers and composites tribology. The book suggests a new approach to explore the effect of applied load and surface defects on the fatigue wear behaviour of polymers, using a new tribometer and thorough experiments. It discusses effects of surface cracks, under different static and cyclic loading parameters on wear, and presents an intelligent algorithm, in the form of a neural network, to map the relations

  20. Wear mechanisms of toughened zirconias

    International Nuclear Information System (INIS)

    Becker, P.C.; Libsch, T.A.; Rhee, S.K.

    1985-01-01

    The dry friction and wear behavior of toughened zirconias against hardened steel was studied using the falex ring and block technique. Three experimental ZrO 2 -Y 2 O 3 ceramics and two commerical ZrO 2 -MgO ceramics were investigated. Each ceramic was tested at 500 and 2000 rpm at normal loads in the range 2.3 to 40.8 kg. Significant trends in the friction and wear data were found correlating composition, test speeds, and loads. Microstructural examination of the ring, ceramic block, and wear debris has shown that the wear process is very complex and incorporates a number of mechanisms

  1. Regionalization of monthly rainfall erosivity patternsin Switzerland

    Science.gov (United States)

    Schmidt, Simon; Alewell, Christine; Panagos, Panos; Meusburger, Katrin

    2016-10-01

    One major controlling factor of water erosion is rainfall erosivity, which is quantified as the product of total storm energy and a maximum 30 min intensity (I30). Rainfall erosivity is often expressed as R-factor in soil erosion risk models like the Universal Soil Loss Equation (USLE) and its revised version (RUSLE). As rainfall erosivity is closely correlated with rainfall amount and intensity, the rainfall erosivity of Switzerland can be expected to have a regional characteristic and seasonal dynamic throughout the year. This intra-annual variability was mapped by a monthly modeling approach to assess simultaneously spatial and monthly patterns of rainfall erosivity. So far only national seasonal means and regional annual means exist for Switzerland. We used a network of 87 precipitation gauging stations with a 10 min temporal resolution to calculate long-term monthly mean R-factors. Stepwise generalized linear regression (GLM) and leave-one-out cross-validation (LOOCV) were used to select spatial covariates which explain the spatial and temporal patterns of the R-factor for each month across Switzerland. The monthly R-factor is mapped by summarizing the predicted R-factor of the regression equation and the corresponding residues of the regression, which are interpolated by ordinary kriging (regression-kriging). As spatial covariates, a variety of precipitation indicator data has been included such as snow depths, a combination product of hourly precipitation measurements and radar observations (CombiPrecip), daily Alpine precipitation (EURO4M-APGD), and monthly precipitation sums (RhiresM). Topographic parameters (elevation, slope) were also significant explanatory variables for single months. The comparison of the 12 monthly rainfall erosivity maps showed a distinct seasonality with the highest rainfall erosivity in summer (June, July, and August) influenced by intense rainfall events. Winter months have the lowest rainfall erosivity. A proportion of 62 % of

  2. Improved single- and multi-contact life-time testing of dental restorative materials using key characteristics of the human masticatory system and a force/position-controlled robotic dental wear simulator.

    Science.gov (United States)

    Raabe, D; Harrison, A; Ireland, A; Alemzadeh, K; Sandy, J; Dogramadzi, S; Melhuish, C; Burgess, S

    2012-03-01

    This paper presents a new in vitro wear simulator based on spatial parallel kinematics and a biologically inspired implicit force/position hybrid controller to replicate chewing movements and dental wear formations on dental components, such as crowns, bridges or a full set of teeth. The human mandible, guided by passive structures such as posterior teeth and the two temporomandibular joints, moves with up to 6 degrees of freedom (DOF) in Cartesian space. The currently available wear simulators lack the ability to perform these chewing movements. In many cases, their lack of sufficient DOF enables them only to replicate the sliding motion of a single occlusal contact point by neglecting rotational movements and the motion along one Cartesian axis. The motion and forces of more than one occlusal contact points cannot accurately be replicated by these instruments. Furthermore, the majority of wear simulators are unable to control simultaneously the main wear-affecting parameters, considering abrasive mechanical wear, which are the occlusal sliding motion and bite forces in the constraint contact phase of the human chewing cycle. It has been shown that such discrepancies between the true in vivo and the simulated in vitro condition influence the outcome and the quality of wear studies. This can be improved by implementing biological features of the human masticatory system such as tooth compliance realized through the passive action of the periodontal ligament and active bite force control realized though the central nervous system using feedback from periodontal preceptors. The simulator described in this paper can be used for single- and multi-occlusal contact testing due to its kinematics and ability to exactly replicate human translational and rotational mandibular movements with up to 6 DOF without neglecting movements along or around the three Cartesian axes. Recorded human mandibular motion and occlusal force data are the reference inputs of the simulator

  3. Improved single- and multi-contact life-time testing of dental restorative materials using key characteristics of the human masticatory system and a force/position-controlled robotic dental wear simulator

    International Nuclear Information System (INIS)

    Raabe, D; Dogramadzi, S; Melhuish, C; Harrison, A; Alemzadeh, K; Burgess, S; Ireland, A; Sandy, J

    2012-01-01

    This paper presents a new in vitro wear simulator based on spatial parallel kinematics and a biologically inspired implicit force/position hybrid controller to replicate chewing movements and dental wear formations on dental components, such as crowns, bridges or a full set of teeth. The human mandible, guided by passive structures such as posterior teeth and the two temporomandibular joints, moves with up to 6 degrees of freedom (DOF) in Cartesian space. The currently available wear simulators lack the ability to perform these chewing movements. In many cases, their lack of sufficient DOF enables them only to replicate the sliding motion of a single occlusal contact point by neglecting rotational movements and the motion along one Cartesian axis. The motion and forces of more than one occlusal contact points cannot accurately be replicated by these instruments. Furthermore, the majority of wear simulators are unable to control simultaneously the main wear-affecting parameters, considering abrasive mechanical wear, which are the occlusal sliding motion and bite forces in the constraint contact phase of the human chewing cycle. It has been shown that such discrepancies between the true in vivo and the simulated in vitro condition influence the outcome and the quality of wear studies. This can be improved by implementing biological features of the human masticatory system such as tooth compliance realized through the passive action of the periodontal ligament and active bite force control realized though the central nervous system using feedback from periodontal preceptors. The simulator described in this paper can be used for single- and multi-occlusal contact testing due to its kinematics and ability to exactly replicate human translational and rotational mandibular movements with up to 6 DOF without neglecting movements along or around the three Cartesian axes. Recorded human mandibular motion and occlusal force data are the reference inputs of the simulator

  4. Dental erosion in archaeological human remains: A critical review of literature and proposal of a differential diagnosis protocol.

    Science.gov (United States)

    Coupal, Isabelle; Sołtysiak, Arkadiusz

    2017-12-01

    Although studies of dental wear on archaeological human remains have largely focused on mechanical wear (attrition and abrasion) in the past, chemical wear (erosion) is being increasingly identified as a separate form of wear. This paper aims to review the current state of research and to develop a protocol that may be universally used by biorchaeologists to specifically identify dental erosion. A critical review of literature has been done in order to highlight the issues related to diagnosis of dental erosion in archaeological human remains. The bodies of work based on the analysis of both modern and archaeological dentitions raise their separate problems. In addition to a need to re-evaluate symptoms of dental erosion, notably dentin 'cupping', it is apparent that no specific protocol is adapted from medical to archaeological sciences. Authors rather rely on tooth wear indices and photographs of modern clinical cases for diagnosis. Furthermore, the diagenetic chemical alternation has rarely been considered as a bias. Here we suggest a three-step protocol: the primary method is the microscopic identification of dental erosion by SEM, followed by the exclusion of taphonomic aetiology on surrounding bone and soil pH analysis. Archaeologists should also explore possible causative agents of wear using archaeological and historic knowledge about the population being analyzed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Characterization of wear debris from metal-on-metal hip implants during normal wear versus edge-loading conditions.

    Science.gov (United States)

    Kovochich, Michael; Fung, Ernest S; Donovan, Ellen; Unice, Kenneth M; Paustenbach, Dennis J; Finley, Brent L

    2018-04-01

    Advantages of second-generation metal-on-metal (MoM) hip implants include low volumetric wear rates and the release of nanosized wear particles that are chemically inert and readily cleared from local tissue. In some patients, edge loading conditions occur, which result in higher volumetric wear. The objective of this study was to characterize the size, morphology, and chemistry of wear particles released from MoM hip implants during normal (40° angle) and edge-loading (65° angle with microseparation) conditions. The mean primary particle size by volume under normal wear was 35 nm (range: 9-152 nm) compared with 95 nm (range: 6-573 nm) under edge-loading conditions. Hydrodynamic diameter analysis by volume showed that particles from normal wear were in the nano- (edge-loading conditions generated particles that ranged from Edge-loading conditions generated more elongated particles (4.5%) (aspect ratio ≥ 2.5) and more CoCr alloy particles (9.3%) compared with normal wear conditions (1.3% CoCr particles). By total mass, edge-loading particles contained approximately 640-fold more cobalt than normal wear particles. Our findings suggest that high wear conditions are a potential risk factor for adverse local tissue effects in MoM patients who experience edge loading. This study is the first to characterize both the physical and chemical characteristics of MoM wear particles collected under normal and edge-loading conditions. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 986-996, 2018. © 2017 Wiley Periodicals, Inc.

  6. Assessment of wear facets produced by the ACTA wear machine

    DEFF Research Database (Denmark)

    Benetti, Ana R; Larsen, Liselotte; Dowling, Adam H

    2016-01-01

    . The mean wear depth was measured using the traditionally employed 2D and compared with the 3D profilometric (digital) techniques. Data were submitted to analyses of variance, Tukey's post hoc tests and Independent Samples Student's t-tests (where appropriate) at p...OBJECTIVE: To investigate the use of a three-dimensional (3D) digital scanning method in determining the accuracy of the wear performance parameters of resin-based composites (RBCs) determined using a two-dimensional (2D) analogue methodology following in-vitro testing in an Academisch Centrum...... for Tandheelkunde Amsterdam (ACTA) wear machine. METHODS: Specimens compatible with the compartments of the ACTA wear machine specimen wheel (n=10) were prepared from one commercial and four experimental RBCs. The RBC specimens were rotated against an antagonist wheel in a food-like slurry for 220,000 wear cycles...

  7. Dental erosion: Prevalence and severity among 16-year-old adolescents in Troms, Norway.

    Science.gov (United States)

    Mulic, A; Fredriksen, Ø; Jacobsen, I D; Tveit, A B; Espelid, I; Crossner, C G

    2016-09-01

    To study the prevalence, distribution and severity of dental erosion among 16-year-old adolescents in the Troms region of Norway. Study design: The participants were recruited through the Tromsø-study ("Fit Futures"), and 392 16-year-olds were examined for dental erosion using clinical intraoral photographs. Three calibrated clinicians used the Visual Erosion Dental Examination (VEDE) system to register and grade the dental erosive wear. More than one third (38%) of the participants showed dental erosion on at least one tooth surface, 18% were limited to the enamel, while 20% of the adolescents showed erosive wear extending into the dentine. The occlusal surfaces of the lower first molars, and the palatal surfaces of the maxillary incisors were the most often and most severely affected. Of the participants showing dental erosion, 93% exhibited "cuppings" on the molars, with 48% limited to the enamel and 52% extending into the dentine. The highest prevalence of "cuppings" (73%) was found on the first lower molars, especially the mesiobuccal cusp of the teeth. The prevalence and severity of dental erosion was found to be higher in male than in female participants (p dental erosion among adolescents in Troms and stress the importance of information, early and effective diagnostics and implementation of prevention strategies.

  8. Protection from erosion following wildfire

    Science.gov (United States)

    Peter R. Robichaud; William J. Elliot

    2006-01-01

    Erosion in the first year after a wildfire can be up to three orders of magnitude greater than the erosion from undisturbed forests. To mitigate potential postfire erosion, various erosion control treatments are applied on highly erodible areas with downstream resources in need of protection. Because postfire erosion rates generally decline by an order of magnitude for...

  9. Erosion and stability of a mine soil

    International Nuclear Information System (INIS)

    Wu, T.H.; Stadler, A.T.; Low, C.

    1996-01-01

    Mine soils developed from mine spoils commonly have a wide range of particle size. The slopes of old spoil piles usually are marked by gullies due to years of uncontrolled erosion. These characteristics raise questions about applicability of available theories and models for estimating runoff and erosion. An investigation was made to determine whether available erosion models can work for mine soils and can account for gully erosion. The investigation at an abandoned surface mine consisted of measurement of soil and sediment properties, measurement of runoff and erosion, observations of armor by rock fragments on gully floor, and calculations with available theories of sediment transport and slope stability. The results at this site suggest that (1) predictions with the ANSWERS model have about the same accuracy as those made for agricultural lands; (2) armor provided by rock fragments are temporary as they are periodically removed by debris flows; (3) detachment by rainfall impact is the primary cause of erosion on short steep slopes; and (4) a simplified method can be used for estimating erosion on such slopes

  10. Tyre and road wear prediction

    NARCIS (Netherlands)

    Lupker, H.A.

    2003-01-01

    Both tyre wear and road polishing are complex phenomenon, which are obviously strongly related; the energy that polishes the road is the energy that wears the tyre. The both depend non-linearly on numerous parameters, like materials used, vehicle and road usage, environmental conditions (i.e.

  11. Scales and erosion

    Science.gov (United States)

    There is a need to develop scale explicit understanding of erosion to overcome existing conceptual and methodological flaws in our modelling methods currently applied to understand the process of erosion, transport and deposition at the catchment scale. These models need to be based on a sound under...

  12. Characterizing soil erosion potential using electrical resistivity imaging : final report.

    Science.gov (United States)

    2017-04-01

    The erosion rate, or erodibility, of soil depends on many soil characteristics including: plasticity, : water content, grain size, percent clay, compaction, and shear strength. Many of these characteristics also : influence soil in situ bulk electric...

  13. Characterizing soil erosion potential using electrical resistivity imaging : technical summary.

    Science.gov (United States)

    2017-04-01

    The erosion rate, or erodibility, of soil depends on many soil characteristics : including: plasticity, water content, grain size, percent clay, compaction, and shear : strength. Many of these characteristics also influence soil in situ bulk electric...

  14. Impact fretting wear in CO2-based environments

    International Nuclear Information System (INIS)

    Levy, G.; Morri, J.

    1985-01-01

    An impact wear model, based on the load-sliding distance proportionality of wear and the mechanical response of the impacting bodies, was derived and tested against experiment. The experimental work was carried out on a twin vibrator rig capable of repetitive impact of a moving specimen against a stationary target material. The impact wear characteristics of three materials (mild steel, 9Cr-1Mo steel and austenitic 316 steel) against 310 stainless steel were examined over a range of temperatures (18-600 0 C). Additionally the effects of variations in the mechanical parameters (incident energy, ξ i , number N of impacts and angle of incidence φ) as a function of temperature were evaluated for mild steel only. The model was verified for impacting within a stable wear regime at 100 0 C for 9Cr-1Mo steel. The emergence of a severe-to-mild wear transition at elevated temperatures (200-400 0 C), however, introduced an energy and a 'numbers of cycles' effect that caused apparent deviations from theory. It was concluded that for stable single-mechanism wear regimes (metallic, oxidative etc.) oblique elastic impacts with a gross slip component were accurately described by the proposed impact wear model. (orig.)

  15. The Effect of Rainfall Intensity on Soil Erosion and Runoff for Latosol Soil in Indonesia

    OpenAIRE

    Sukartaatmadja, Sukandi; Sato, Yohei; Yamaji, Eiji; Ishikawa, Masaya

    2003-01-01

    Soil erosion is the most serious problem of land degradation in Indonesia. However, limited report has been documented. The erosion problem in Indonesia, particularly in Java, has been at an alarming rate. The fundamental 1 case of soil erosion is the rain effect upon the soil. Rainfall intensity and soil characteristics are related to soil erosion and runoff The objective of this research was to study the relationship of rainfall intensity, soil erosion and runoff in latosol s...

  16. Numerical study of impact erosion of multiple solid particle

    Science.gov (United States)

    Zheng, Chao; Liu, Yonghong; Chen, Cheng; Qin, Jie; Ji, Renjie; Cai, Baoping

    2017-11-01

    Material erosion caused by continuous particle impingement during hydraulic fracturing results in significant economic loss and increased production risks. The erosion process is complex and has not been clearly explained through physical experiments. To address this problem, a multiple particle model in a 3D configuration was proposed to investigate the dynamic erosion process. This approach can significantly reduce experiment costs. The numerical model considered material damping and elastic-plastic material behavior of target material. The effects of impact parameters on erosion characteristics, such as plastic deformation, contact time, and energy loss rate, were investigated. Based on comprehensive studies, the dynamic erosion mechanism and geometry evolution of eroded crater was obtained. These findings can provide a detailed erosion process of target material and insights into the material erosion caused by multiple particle impingement.

  17. Numerical and experimental investigations on cavitation erosion

    Science.gov (United States)

    Fortes Patella, R.; Archer, A.; Flageul, C.

    2012-11-01

    A method is proposed to predict cavitation damage from cavitating flow simulations. For this purpose, a numerical process coupling cavitating flow simulations and erosion models was developed and applied to a two-dimensional (2D) hydrofoil tested at TUD (Darmstadt University of Technology, Germany) [1] and to a NACA 65012 tested at LMH-EPFL (Lausanne Polytechnic School) [2]. Cavitation erosion tests (pitting tests) were carried out and a 3D laser profilometry was used to analyze surfaces damaged by cavitation [3]. The method allows evaluating the pit characteristics, and mainly the volume damage rates. The paper describes the developed erosion model, the technique of cavitation damage measurement and presents some comparisons between experimental results and numerical damage predictions. The extent of cavitation erosion was correctly estimated in both hydrofoil geometries. The simulated qualitative influence of flow velocity, sigma value and gas content on cavitation damage agreed well with experimental observations.

  18. Erosion by rain in the western Congo

    International Nuclear Information System (INIS)

    Ploey, J. de

    1967-01-01

    Vast expanses of the western part of central and southern Africa are covered with uniform, sandy formations of the Kalahari type. The topography of these areas and their present morphological characteristics are mainly the result of erosion by rain. Information on the hydrology of the surface waters in these areas is fairly limited and is insufficient to permit any conclusions regarding the way in which erosion by rain takes place. To obtain a better understanding of these phenomena, the author devised a series of experiments based on the use of 46 Sc-labelled radioactive sand. These experiments began at the beginning of the 1964/65 rainy season and are continuing. The experimental plot corresponds to convex and rectilinear portions of a hillside with a slope varying between 0 and 12 degrees. The vegetation consists of grassy savannah of substeppe appearance and secondary forests. Series of labelled samples were placed successively on the surface of the experimental plot and the erosive effect of rain was determined by measuring the residual concentrations after rainfall. Some samples were placed below a shield so as to eliminate the effects of splash and reveal the part played by runoff. Radiographic films were used to study the dispersion of labelled particles in the surrounding area. This radiographic method made it possible to determine the scale of erosion by splash for different rainfall conditions. The erosion diagrams obtained from these experiments show the correlations that exist between the intensity and duration of the rainfall and the erosion of the soil. Examination of the erosion diagrams and the shielded samples and analysis of the radiographs showed that erosion by rain on Kalahari ground covered with substeppe savannah is caused mainly by splash erosion and by dispersed, intermittent runoff. Sheet wash plays no part if the slope is less than 12 degrees. (author) [fr

  19. Research on Oxidation Wear Behavior of a New Hot Forging Die Steel

    Science.gov (United States)

    Shi, Yuanji; Wu, Xiaochun

    2018-01-01

    Dry sliding tests for the hot forging die steel DM were performed in air under the test temperature at 400-700 °C and the time of 0.5-4 h by a UMT-3 high-temperature wear tester. The wear behavior and characteristics were studied systematically to explore the general characters in severe oxidation conditions. The results showed that a mild-to-severe oxidation wear transition occurred with an increase in the test temperature and duration. The reason was clarified as the unstable M6C carbides coarsening should be responsible for the severe delamination of tribo-oxide layer. More importantly, an intense oxidation wear with lower wear rates was found when the experimental temperature reaches 700 °C or after 4 h of test time at 600 °C, which was closely related to the degradation behavior during wear test. Furthermore, a new schematic diagram of oxidation wear of DM steel was proposed.

  20. Test installation for studying erosion-corrosion of metals for coal washing plants

    Energy Technology Data Exchange (ETDEWEB)

    Hoey, G. R.; Dingley, W.; Wiles, C. T.

    1979-02-15

    A test installation was constructed for investigating erosion-corrosion of metals by coal-water slurries. Erosion-corrosion tests of mild steel panels were conducted using slurries of alundum, quartz, washed coal and coal refuse. Wear rates were found to depend on type of abrasive, particle size and water conductivity and were reduced by cathodic protection and inhibitors. Cathodic protection of mild steel in coal slurries containing sulphate ion reduced wear by 90% and 86% for stationary and rotating panels, respectively. This study has demonstrated that the successful application of corrosion control techniques would reduce metal wastage in coal washing plants. The test installation is considered suitable for developing the techniques.

  1. Pipe bend wear - is tungsten carbide the answer?

    International Nuclear Information System (INIS)

    Freinkel, D.

    1988-01-01

    The purpose of the investigation was to compare the relative wear resistance of various grades of sintered tungsten carbide liners against a mild steel standard in a full-scale pneumatic conveying testing rig. Speciments ranging in cobalt content from 6 to 30 per cent and in grain size from 0,56 to 2,98 microns, including a mild steel standard, were placed on a specially designed holder which fitted into a tee type 100 mm diameter bend. The specimens were tested under various operating conditions, ie air velocity ranging from 28m/s to 52m/s, impact angles of 30 0 to 70 0 mass flow rates of 35kg/min to 83kg/min and phase densities of 1,2 to 2,9, using a 4 mm nominal size crushed granite rock. The experimental results show that the ultrafine-grained, low cobalt (6 per cent) tungsten carbide displays little sensitivity to varying velocities, impact angles, mass flow rates or phase densities, and consistently gave the best wear resistance under all testing conditions. It consistently showed the least wear resistance under all testing conditions and performed only slightly better than mild steel. The effect of the carbide grain size was found to be small, although the finer grain sizes displayed greater wear resistance than the coarse grains. The effect of cobalt content was such that the lower cobalt specimens (6 per cent range) consistently performed better than the higher cobalt contents (10 per cent, 15 per cent, 30 per cent) under all testing conditions; the wear resistance decreasing with increasing cobalt content. An empirical model for the prediction of wear for each type of material tested has been proposed, given the particular operating conditions. Microstructurally it has been shown that there is a definite relationship between erosion resistance and the inverse of the magnetic coercivity of the tungsten carbide alloys

  2. Diagnosis and management of maxillary incisors affected by incisal wear: an interdisciplinary case report.

    Science.gov (United States)

    Bernardo, Jussara Karina; Maia, Elaine A Vilela; Cardoso, Antônio Carlos; de Araújo Júnior, Edson Medeiros; Monteiro Júnior, Sylvio

    2002-01-01

    In the attempt to restore anterior teeth affected by erosion and bruxism, many clinicians have been frustrated with the constant restorative failures. Frequently, these failures are attributed to the restorative materials employed, especially in cases in which composite resins are used. However, some flaws of the restorations are related to the oversight of occlusal principles. The purpose of this article is to discuss the etiology, signs, and symptoms of incisal wear, with special attention to that caused by bruxism and chemical erosion. Relatively simple management techniques (e.g., occlusal adjustment, adhesive restorations) are proposed, and the diagnosis and management of a representative clinical case is presented. In some cases of bruxism and/or dental erosion, it is possible to acquire space to recuperate the esthetics and function of maxillary incisors affected by incisal wear through a conservative treatment associated with the control of the etiologic factors.

  3. Corrosion and wear resistant metallic layers produced by electrochemical methods

    DEFF Research Database (Denmark)

    Christoffersen, Lasse; Maahn, Ernst Emanuel

    1999-01-01

    Corrosion and wear-corrosion properties of novel nickel alloy coatings with promising production characteristics have been compared with conventional bulk materials and hard platings. Corrosion properties in neutral and acidic environments have been investigated with electrochemical methods....... Determination of polarisation resistance during 100 hours followed by stepwise anodic polarisation seems to be a promising technique to obtain steady state data on slowly corroding coatings with transient kinetics. A slurry test enables determination of simultaneous corrosion and abrasive wear. Comparison...... of AISI 316, hard chromium and hardened Ni-P shows that there is no universal correlation between surface hardness and wear-corrosion loss. The possible relation between questionable passivity of Ni-P coatings and their high wear-corrosion loss rate compared to hard chromium is discussed....

  4. Dental erosion among 12-14 year old school children in Khartoum: a pilot study.

    Science.gov (United States)

    El Karim, I A; Sanhouri, N M; Hashim, N T; Ziada, H M

    2007-09-01

    To investigate dental erosion among 12-14 year old Sudanese school children and evaluate the associated risk factors. Cross sectional survey in secondary schools in Khartoum city, Sudan. A sample of 157 school children was obtained from both private and public schools. Erosion on the labial and palatal surfaces of maxillary incisors was measured by criterion based on the Smith and Knight Tooth Wear Index. Dietary intake and other related factors were assessed using a questionnaire. The overall erosion prevalence in this group was 66.9%, of which 45.2% was mild and 21.7% was moderate erosion. A strong association was found between erosion and private schooling (higher socioeconomic groups), carbonated drinks, herbal hibiscus drink and traditional acidic food consumption. There was a high prevalence of dental erosion among Sudanese school children which was mild to moderate in severity and was strongly associated with acidic dietary intake

  5. Performance of HVOF carbide coatings under erosion/corrosion

    International Nuclear Information System (INIS)

    Simard, S.; Arsenault, B.; Legoux, J.G.; Hawthorne, H.M.

    1999-01-01

    Cermet based materials are known to have an excellent performance under several wear conditions. High velocity oxy-fuel (HVOF) technology allows the deposition of such hard materials in the form of protective coatings onto different surfaces. Under slurry erosion, the performance of the coatings is influenced by the occurrence of corrosion reactions on the metallic matrix. Indeed, wet conditions promote the dissolution of metallic binder resulting in a potential synergic effect between the corrosion and wear mechanisms. The composition of the metallic matrix plays a key role on the stability of the coatings and their degradation rate. In this work, four coatings based on tungsten carbide embedded in different metallic binders were evaluated with regard to corrosion and wear. (author)

  6. Modelling of environmental and climatic problems: Wind and water erosion

    International Nuclear Information System (INIS)

    Aslan, Z.

    2004-01-01

    Magnitude of wind and water erosion mainly depend on wind velocity, rainfall rate, slope and soil characteristics. The main purpose of this lecture is to define the role of small, meso and large scale phenomena (local and synoptic fluctuations) on water and wind erosion. These lecture notes present some results on wind speed simulation and seasonal fluctuations of water deficit for the selected station in different erosion risque and transition regions of Turkey. (author)

  7. Relationship between food habits and tooth erosion occurrence in Malaysian University students.

    Science.gov (United States)

    Manaf, Zahara Abdul; Lee, Mei Tee; Ali, Nor Hazirah Muhammad; Samynathan, Selvamary; Jie, Ying Phor; Ismail, Noor Hasnani; Bibiana Hui Ying, Yong; Wei Seng, Yeo; Yahya, Nurul Asyikin

    2012-04-01

    Tooth erosion is a growing dental problem; however, the role of diet in the aetiology of tooth erosion is unclear. A cross-sectional study was conducted to determine the association between tooth erosion occurrence and the consumption of acidic foods and drinks among undergraduate university students. A total of 150 undergraduate students (33 males and 117 females) aged 19 to 24 years at Universiti Kebangsaan Malaysia participated in this study. The Basic Erosive Wear Examination was used to assess the occurrence of tooth erosion. Information regarding dental hygiene practices, usual dietary habits, and consumption of acidic foods and drinks was obtained through a structured questionnaire. In all, 68% of subjects had tooth erosion. Subjects who reported having received information about healthy eating were less likely to have tooth erosion (χ(2) [1, N = 150] = 7.328, P = 0.007). The frequencies of milk (OR = 0.29, 95% CI = 0.13-0.67) and tea/coffee (adjusted OR = 0.42, 95% CI = 0.19-0.95) consumption were negatively associated with tooth erosion. Dental hygiene practice, the frequency and amount of acidic food and drink intake, and body mass index classification were not significantly associated with the risk of tooth erosion (P > 0.05). A high prevalence of tooth erosion was observed among this group of students. Preventive measures, such as dietary advice and increased consumption of milk at a younger age, may reduce the occurrence of tooth erosion among this age group.

  8. Simulation of erosion in drilling tools for oil and gas industry

    Energy Technology Data Exchange (ETDEWEB)

    Arefi, B.; Settari, A. [Calgary Univ., AB (Canada); Angman, P. [Tesco Corp., Calgary, AB (Canada)

    2004-07-01

    Erosion in oil well drilling tools is a form of wear which occurs when fluid containing solid particles impacts a solid surface. The intensity of erosion is generally measured as the rate of material removal from the surface, and is expressed as E{sub r}, the weight of material removed by unit weight of impacting particles. Erosion can also be reduced by tool improvement and modification, thereby extending the life of drilling tools. To date, no attempt has been made to model the erosion phenomenon in drilling tools. This paper presents a newly developed erosion simulator which is the first design tool for the drilling industry. This work demonstrates that erosion can be simulated. A model was developed to calibrate the erosion coefficients for drilling tool conditions. The mechanism of erosion can be controlled by the impact velocity and angle. Algorithms were developed for transient simulation of the erosion of any surface in 2-dimensional geometry. The Erosion Simulator has been validated and calibrated against data provided by TESCO Corporation's casing drilling tools. The model has been shown to successfully predict and minimize erosion by modifying the tool geometry and metallurgy. 21 refs., 1 tab., 15 figs.

  9. Comparative evaluation of experimental and theoretical erosion resistance of materials upon electric pulse treatment

    International Nuclear Information System (INIS)

    Karpman, M.G.; Fetisov, G.P.; Bologov, D.V.

    1999-01-01

    Using the Palatnik criterion a comparative analysis is performed of the theoretical and experimental data on comparative electric erosion and erosion resistance of the electrodes and parts made of different materials upon their treatment using electric pulse technique. A reasonable qualitative agreement of the theoretical and experimental data indicates the possibility of using the Palatnik criterion to predict the serviceability of different pairs of the materials in conditions of electroerosion wear [ru

  10. Microstructure and elevated-temperature erosion-oxidation behaviour of aluminized 9Cr-1Mo Steel

    OpenAIRE

    Huttunen, E.; Honkanen, M.; Tsipas, Sophia Alexandra; Omar, H.; Tsipas, D.

    2012-01-01

    Degradation of materials by a combination of erosive wear and atmospheric oxidation at elevated temperatures constitutes a problem in some power generation processes, such as fluidized-bed combustion. In this work, 9Cr-1Mo steel, a common tube material in combustion chambers, is coated by a pack cementation method from an Al-containing pack in order to improve the resistance to erosion-oxidation at elevated temperatures. The resulting coating is studied in terms of microstructure and microhar...

  11. Friction and wear behavior of steam-oxidized ferrous PM compacts

    Energy Technology Data Exchange (ETDEWEB)

    Raj, P. Philomen-D-Anaand; GopalaKrishna, A. [Dept. of Mechanical Engineering, Jawaharlal Nehru Technological University, Kakinada (India); Palaniradja, K [Dept. of Mechanical Engineering, Pondicherry Engineering College, Pondicherry (India)

    2016-10-15

    This study determines density effect by assessing sintering temperature and graphite content on the dry sliding wear characteristics of steam-treated iron materials using a pin-on-disk wear test. The specimens were prepared from atomized premixed iron base powders and contained 0.1 to 1.0 wt.% carbon compacted at different densities (5.9 g/cc to 6.8 g/cc). The specimens were sintered for 1 h at different sintering temperatures (1090°C to 1130°C), and then subjected to continuous steam treatment at 540°C for 95 min through in situ Powder metallurgy (PM) technique. Steam treatment was proposed to improve the wear performances of the components of PM. Wear tests were conducted using a pin-on-disk-type machine. Load ranged from 20 N to 60 N. Sliding distance and sliding velocity of 312 m and 0.26 m/s, respectively, were adopted for all tests. Scanning electron microscope was used to analyze wear surface. Increased density and graphite content reduced the wear rate of steam-treated materials. Hardness increased with increasing graphite content. Wear mechanism, wear rate map, and wear maps were drawn for the test result data. Wear transition map identified mild, severe, and ultra-severe wear regimes as functions of applied load.

  12. Rubber glove wearing device

    International Nuclear Information System (INIS)

    Nozaki, Tatsuo; Takada, Kaoru.

    1994-01-01

    Rubber groves are attached each to an upper end of a glove putting vessel having an air-sucking hole on the bottom by enlarging an opening end of the rubber glove and turning back the inside to the outside. When the sucking device is operated, air in the glove putting device is sucked and the rubber glove is expanded by an atmospheric pressure. After expansion of the rubber glove to some extent, the sucking device is stopped, and presence or absence of failures of the rubber glove is confirmed by shrinkage of the rubber glove and by an indication value of a pressure gauge for detecting the pressure change in the vessel. Then, a hand is inserted to the expanded rubber glove, and a detaching switch in the vessel is pushed by a finger tip. A detaching piece at the upper end of the vessel is protruded outwardly to enlarge the turned-back portion of the rubber glove to easily release the rubber glove from the putting vessel, and the rubber glove is put on. This enables to wear the rubber glove and conduct failure test simultaneously. Further, a user can put on the rubber glove without touching the outside of the rubber glove. (I.N.)

  13. Effect of corrosion protective coatings on compressor blades affected by different erosive exposures

    International Nuclear Information System (INIS)

    Happle, T.W.

    1989-01-01

    It was the task of this dissertation to examine and to classify the inorganically bonded aluminum coatings with regard to their suitability as a coating for compressor blades for stationary gas turbines and aerojet engines. Industrial aluminum coatings bonded inorganically were used for the tests. Comparative examinations were done with diffusion-deposited aluminum layers as well as with aluminum layers precipitated electrolytically, and with modified inorganically bonded aluminum coatings (with additional TiN protective coating). The examination program was subdivided into two main tasks: Suitability tests and examination of corrosion fatigue. The suitability tests covered corrosion examinations (with salt spray and intermittent immersion tests), electrochemically controlled corrosion assessments (pitting corrosion behavior) and erosion assessments (erosive and abrasive wear tests). Experimental material was mainly the commercial compressor blade steel X20Cr13, and sample tests were carried out with the higher-strength steel X10CrNiMoV12 2 2. For the practical examination of the erosion resistance of the aluminum coatings, it was required to develop an erosion testing method. It was designed as an erosive and abrasive wear testing method with solid-face fluidized bed. The testing method makes it possible to pre-set all relevant quantities which influence the erosive and abrasive wear. (orig./MM) [de

  14. Erosion resistance of FeAl-TiB2 and FeAl-WC at room and elevated temperatures

    International Nuclear Information System (INIS)

    Alman, D.E.; Tylczak, J.H.; Hawk, J.A.

    2000-01-01

    The resistance of FeAl-40%TiB 2 and FeAl-80%WC cermets to solid particle erosion at 25, 180, 500 and 700 C was evaluated and compared to the behavior of WC-6%Co (Co-90%WC) cemented carbides. Even though the WC-Co contained a higher volume fraction of the hard phase, the erosion rates of the FeAl-cermets were similar in magnitude to the erosion rates of the WC-Co. However, the erosion rates of the FeAl-cermets either were constant (FeAl-TiB 2 ) or decreased (FeAl-WC) with increasing test temperature; whereas, the erosion rates of the WC-Co cemented carbides increased with increasing test temperature. This indicated that once the microstructures of the FeAl-cermets are optimized for wear resistance, these materials might make promising candidates for high-temperature wear applications

  15. Measurement of erosion: Is it possible?

    NARCIS (Netherlands)

    Stroosnijder, L.

    2005-01-01

    Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation

  16. Numerical modelling of concentrated leak erosion during Hole Erosion Tests

    OpenAIRE

    Mercier, F.; Bonelli, S.; Golay, F.; Anselmet, F.; Philippe, P.; Borghi, R.

    2015-01-01

    This study focuses on the numerical modelling of concentrated leak erosion of a cohesive soil by a turbulent flow in axisymmetrical geometry, with application to the Hole Erosion Test (HET). The numerical model is based on adaptive remeshing of the water/soil interface to ensure accurate description of the mechanical phenomena occurring near the soil/water interface. The erosion law governing the interface motion is based on two erosion parameters: the critical shear stress and the erosion co...

  17. Nodal wear model: corrosion in carbon blast furnace hearths

    International Nuclear Information System (INIS)

    Verdeja, L. F.; Gonzalez, R.; Alfonso, A.; Barbes, M. F.

    2003-01-01

    Criteria developed for the Nodal Wear Model (NWM) were applied to estimate the shape of the corrosion profiles that a blast furnace hearth may acquire during its campaign. Taking into account design of the hearth, the boundary conditions, the characteristics of the refractory materials used and the operation conditions of the blast furnace, simulation of wear profiles with central well, mushroom and elephant foot shape were accomplished. The foundations of the NWM are constructed considering that the corrosion of the refractory is a function of the temperature present at each point (node) of the liquid metal-refractory interface and the corresponding physical and chemical characteristics of the corrosive fluid. (Author) 31 refs

  18. Techniques to Evaluate Dental Erosion: A Systematic Review of Literature.

    Science.gov (United States)

    Joshi, Mahasweta; Joshi, Nikhil; Kathariya, Rahul; Angadi, Prabhakar; Raikar, Sonal

    2016-10-01

    This article reviews different techniques for evaluating dental erosion, weighs the advantages and disadvantages of these techniques, and presents the latest trends in the study of dental erosion. In May 2014, an initial search was carried out in the PubMed/MEDLINE database of indexed journals from 1975 to 2013 using the following keywords: dental erosion; dental erosion In-vitro; and dental erosion in-vivo. Bibliographic citations from the papers found were then used to find other useful sources. The authors categorize the techniques into three classes: in-vitro, in-vivo and in-vitro/in-vivo. The article discusses the instrumentation required to use each of these techniques, as well as their rationale, merits and applications. The emergence of in-vitro/in-vivo techniques offers the potential to accurately quantify tooth wear in clinical situations. Cross-sectional as well as longitudinal studies show that these techniques will improve diagnosis, treatment planning and management of dental erosion.

  19. Wear mechanisms of coated hardmetals

    International Nuclear Information System (INIS)

    Richter, V.

    2001-01-01

    In the paper several aspects of the wear mechanisms of coated hardmetals, ceramics and super-hard materials (CBN) in machining cast iron are discussed, with particular attention being given to high-speed machining of different cast iron grades. The influence of machining parameters, microstructure, composition and mechanical and chemical properties of the cutting tool and the work-piece material on wear are considered. (author)

  20. Gear Tooth Wear Detection Algorithm

    Science.gov (United States)

    Delgado, Irebert R.

    2015-01-01

    Vibration-based condition indicators continue to be developed for Health Usage Monitoring of rotorcraft gearboxes. Testing performed at NASA Glenn Research Center have shown correlations between specific condition indicators and specific types of gear wear. To speed up the detection and analysis of gear teeth, an image detection program based on the Viola-Jones algorithm was trained to automatically detect spiral bevel gear wear pitting. The detector was tested using a training set of gear wear pictures and a blind set of gear wear pictures. The detector accuracy for the training set was 75 percent while the accuracy for the blind set was 15 percent. Further improvements on the accuracy of the detector are required but preliminary results have shown its ability to automatically detect gear tooth wear. The trained detector would be used to quickly evaluate a set of gear or pinion pictures for pits, spalls, or abrasive wear. The results could then be used to correlate with vibration or oil debris data. In general, the program could be retrained to detect features of interest from pictures of a component taken over a period of time.

  1. Tool wear of a single-crystal diamond tool in nano-groove machining of a quartz glass plate

    International Nuclear Information System (INIS)

    Yoshino, Masahiko; Nakajima, Satoshi; Terano, Motoki

    2015-01-01

    Tool wear characteristics of a diamond tool in ductile mode machining are presented in this paper. Nano-groove machining of a quartz glass plate was conducted to examine the tool wear rate of a single-crystal diamond tool. Effects of lubrication on the tool wear rate were also evaluated. A numerical simulation technique was developed to evaluate the tool temperature and normal stress acting on the wear surface. From the simulation results it was found that the tool temperature does not increase during the machining experiment. It is also demonstrated that tool wear is attributed to the abrasive wear mechanism, but the effect of the adhesion wear mechanism is minor in nano-groove machining. It is found that the tool wear rate is reduced by using water or kerosene as a lubricant. (paper)

  2. Statistical prediction of AVB wear growth and initiation in model F steam generator tubes using Monte Carlo method

    International Nuclear Information System (INIS)

    Lee, Jae Bong; Park, Jae Hak; Kim, Hong Deok; Chung, Han Sub; Kim, Tae Ryong

    2005-01-01

    The growth of AVB wear in Model F steam generator tubes is predicted using the Monte Carlo Method and statistical approaches. The statistical parameters that represent the characteristics of wear growth and wear initiation are derived from In-Service Inspection (ISI) Non-Destructive Evaluation (NDE) data. Based on the statistical approaches, wear growth model are proposed and applied to predict wear distribution at the End Of Cycle (EOC). Probabilistic distributions of the number of wear flaws and maximum wear depth at EOC are obtained from the analysis. Comparing the predicted EOC wear flaw data with the known EOC data the usefulness of the proposed method is examined and satisfactory results are obtained

  3. Statistical prediction of AVB wear growth and initiation in model F steam generator tubes using Monte Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Bong; Park, Jae Hak [Chungbuk National Univ., Cheongju (Korea, Republic of); Kim, Hong Deok; Chung, Han Sub; Kim, Tae Ryong [Korea Electtric Power Research Institute, Daejeon (Korea, Republic of)

    2005-07-01

    The growth of AVB wear in Model F steam generator tubes is predicted using the Monte Carlo Method and statistical approaches. The statistical parameters that represent the characteristics of wear growth and wear initiation are derived from In-Service Inspection (ISI) Non-Destructive Evaluation (NDE) data. Based on the statistical approaches, wear growth model are proposed and applied to predict wear distribution at the End Of Cycle (EOC). Probabilistic distributions of the number of wear flaws and maximum wear depth at EOC are obtained from the analysis. Comparing the predicted EOC wear flaw data with the known EOC data the usefulness of the proposed method is examined and satisfactory results are obtained.

  4. 3D cutting tool-wear monitoring in the process

    Energy Technology Data Exchange (ETDEWEB)

    Cerce, Luka; Pusavec, Franci; Kopac Janez [University of Ljubljana, Askerceva (Slovenia)

    2015-09-15

    The tool-wear of cutting tools has a very strong impact on the product quality as well as efficiency of the machining processes. Therefore, it in-the process characterization is crucial. This paper presents an innovative and reliable direct measuring procedure for measuring spatial cutting tool-wear with usage of laser profile sensor. The technique provides possibility for determination of 3D wear profiles, as advantage to currently used 2D techniques. The influence of the orientation of measurement head on the accuracy and the amount of captured reliable data was examined and the optimal setup of the measuring system was defined. Further, a special clamping system was designed to mount the measurement device on the machine tool turret. To test the measurement system, tool-life experiment was performed. Additionally, a new tool-life criterion was developed, including spatial characteristics of the tool-wear. The results showed that novel tool-wear and tool-life diagnostic represent objective and robust estimator of the machining process. Additionally, such automation of tool-wear diagnostics on machine tool provides higher productivity and quality of the machining process.

  5. Rainfall erosivity in Europe.

    Science.gov (United States)

    Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale; Meusburger, Katrin; Klik, Andreas; Rousseva, Svetla; Tadić, Melita Perčec; Michaelides, Silas; Hrabalíková, Michaela; Olsen, Preben; Aalto, Juha; Lakatos, Mónika; Rymszewicz, Anna; Dumitrescu, Alexandru; Beguería, Santiago; Alewell, Christine

    2015-04-01

    Rainfall is one the main drivers of soil erosion. The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the R-factor in the USLE model and its revised version, RUSLE. At national and continental levels, the scarce availability of data obliges soil erosion modellers to estimate this factor based on rainfall data with only low temporal resolution (daily, monthly, annual averages). The purpose of this study is to assess rainfall erosivity in Europe in the form of the RUSLE R-factor, based on the best available datasets. Data have been collected from 1541 precipitation stations in all European Union (EU) Member States and Switzerland, with temporal resolutions of 5 to 60 min. The R-factor values calculated from precipitation data of different temporal resolutions were normalised to R-factor values with temporal resolutions of 30 min using linear regression functions. Precipitation time series ranged from a minimum of 5 years to a maximum of 40 years. The average time series per precipitation station is around 17.1 years, the most datasets including the first decade of the 21st century. Gaussian Process Regression (GPR) has been used to interpolate the R-factor station values to a European rainfall erosivity map at 1 km resolution. The covariates used for the R-factor interpolation were climatic data (total precipitation, seasonal precipitation, precipitation of driest/wettest months, average temperature), elevation and latitude/longitude. The mean R-factor for the EU plus Switzerland is 722 MJ mm ha(-1) h(-1) yr(-1), with the highest values (>1000 MJ mm ha(-1) h(-1) yr(-1)) in the Mediterranean and alpine regions and the lowest (<500 MJ mm ha(-1) h(-1) yr(-1)) in the Nordic countries. The erosivity density (erosivity normalised to annual precipitation amounts) was also the highest in Mediterranean regions which implies high risk for erosive events and floods

  6. Combating Wear of ASTM A36 Steel by Surface Modification Using Thermally Sprayed Cermet Coatings

    Directory of Open Access Journals (Sweden)

    Vineet Shibe

    2016-01-01

    Full Text Available Thermal spray coatings can be applied economically on machine parts to enhance their requisite surface properties like wear, corrosion, erosion resistance, and so forth. Detonation gun (D-Gun thermal spray coatings can be applied on the surface of carbon steels to improve their wear resistance. In the present study, alloy powder cermet coatings WC-12% Co and Cr3C2-25% NiCr have been deposited on ASTM A36 steel with D-Gun thermal spray technique. Sliding wear behavior of uncoated ASTM A36 steel and D-Gun sprayed WC-12% Co and Cr3C2-25% NiCr coatings on base material is observed on a Pin-On-Disc Wear Tester. Sliding wear performance of WC-12% Co coating is found to be better than the Cr3C2-25% NiCr coating. Wear performance of both these cermet coatings is found to be better than uncoated ASTM A36 steel. Thermally sprayed WC-12% Co and Cr3C2-25% NiCr cermet coatings using D-Gun thermal spray technique is found to be very useful in improving the sliding wear resistance of ASTM A36 steel.

  7. Wear behavior of Cu-Ag-Cr alloy wire under electrical sliding

    International Nuclear Information System (INIS)

    Jia, S.G.; Liu, P.; Ren, F.Z.; Tian, B.H.; Zheng, M.S.; Zhou, G.S.

    2005-01-01

    The wear behavior of a Cu-Ag-Cr alloy contact wire against a copper-base sintered alloy strip was investigated. Wear tests were conducted under laboratory conditions with a special sliding wear apparatus that simulated train motion under electrical current conditions. The initial microstructure of the Cu-Ag-Cr alloy contact wire was analyzed by transmission electron microscopy. Worn surfaces of the Cu-Ag-Cr alloy wire were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The results indicate that the wear rate of the Cu-Ag-Cr wire increased with increasing electrical current and sliding. Within the studied range of electrical current, the wear rate increases with increasing electrical current and sliding speed. Compared with the Cu-Ag contact wire under the same testing conditions, the Cu-Ag-Cr alloy wire has much better wear resistance. Adhesive, abrasive, and electrical erosion wear are the dominant mechanisms during the electrical sliding processes

  8. Critical component wear in heavy duty engines

    CERN Document Server

    Lakshminarayanan, P A

    2011-01-01

    The critical parts of a heavy duty engine are theoretically designed for infinite life without mechanical fatigue failure. Yet the life of an engine is in reality determined by wear of the critical parts. Even if an engine is designed and built to have normal wear life, abnormal wear takes place either due to special working conditions or increased loading.  Understanding abnormal and normal wear enables the engineer to control the external conditions leading to premature wear, or to design the critical parts that have longer wear life and hence lower costs. The literature on wear phenomenon r

  9. Effects of erosive, cariogenic or combined erosive/cariogenic challenges on human enamel: an in situ/ex vivo study.

    Science.gov (United States)

    Honório, H M; Rios, D; Santos, C F; Magalhães, A C; Buzalaf, M A R; Machado, M A A M

    2008-01-01

    Individuals with cariogenic diet can also consume erosive beverages. Thus, it seems necessary to investigate a possible caries/erosion interaction. To test in situ/ex vivo a combination of these challenges, 11 subjects wore intraoral appliances containing four enamel blocks randomly assigned. In the first 2-week phase, the appliances were immersed in a cola drink 3 times/day. Two blocks were free of plaque (erosion only: EO) and two blocks were covered with plaque (erosion + plaque: EP). In the second 2-week phase, four new blocks were all covered with plaque and subjected to a sucrose solution 8 times/day. Among the four new blocks, two were also subjected to the cola drink 3 times/day (erosion + caries: EC) while the other two were not (caries only: CO). Thus, in EO, the specimens were fixed at the intraoral appliance level. In EP, EC and CO they were fixed 1.0 mm under the appliance level and covered with plastic meshes for dental plaque accumulation. Changes in wear and hardness were measured. Data were tested using ANOVA and Tukey's test (p cariogenic challenges showed less enamel alterations when compared to erosive or cariogenic challenges only. (c) 2008 S. Karger AG, Basel.

  10. Mechanisms of erosion of atherosclerotic plaques.

    Science.gov (United States)

    Quillard, Thibaut; Franck, Grégory; Mawson, Thomas; Folco, Eduardo; Libby, Peter

    2017-10-01

    The present review explores the mechanisms of superficial intimal erosion, a common cause of thrombotic complications of atherosclerosis. Human coronary artery atheroma that give rise to thrombosis because of erosion differ diametrically from those associated with fibrous cap rupture. Eroded lesions characteristically contain few inflammatory cells, abundant extracellular matrix, and neutrophil extracellular traps (NETs). Innate immune mechanisms such as engagement of Toll-like receptor 2 (TLR2) on cultured endothelial cells can impair their viability, attachment, and ability to recover a wound. Hyaluronan fragments may serve as endogenous TLR2 ligands. Mouse experiments demonstrate that flow disturbance in arteries with neointimas tailored to resemble features of human eroded plaques disturbs endothelial cell barrier function, impairs endothelial cell viability, recruits neutrophils, and provokes endothelial cells desquamation, NET formation, and thrombosis in a TLR2-dependent manner. Mechanisms of erosion have received much less attention than those that provoke plaque rupture. Intensive statin treatment changes the characteristic of plaques that render them less susceptible to rupture. Thus, erosion may contribute importantly to the current residual burden of risk. Understanding the mechanisms of erosion may inform the development and deployment of novel therapies to combat the remaining atherothrombotic risk in the statin era.

  11. An Iterative Method for Estimating Airfoil Deformation due to Solid Particle Erosion

    Directory of Open Access Journals (Sweden)

    Valeriu DRAGAN

    2014-04-01

    Full Text Available Helicopter blades are currently constructed with composite materials enveloping honeycomb cores with only the leading and trailing edges made of metal alloys. In some cases, the erosive wear of the bound between the composite skin and metallic leading edge leads to full blade failure. It is therefore the goal of this paper to provide a method for simulating the way an airfoil is deformed through the erosion process. The method involves computational fluid dynamics simulations, scripts for automatic meshing and spreadsheet calculators for estimating the erosion and, ultimately, the airfoil deformation. Further work could include more complex meshing scripts allowing the use of similar methods for turbo-machineries.

  12. Coastal Erosion Control Methods

    Science.gov (United States)

    Greene, V.

    2016-12-01

    Coastal erosion is bad because the ecosystem there will be washed away and the animals could drown or be displaced and have to adapt to a new ecosystem that they are not prepared for. I'm interested in this problem because if there aren't beaches when I grow up I won't be able to do the things I would really like to do. I would like to be a marine biologist. Secondly, I don't want to see beach houses washed away. I would like to see people live in harmony with their environment. So, to study ways in which to preserve beaches I will make and use models that test different erosion controls. Two different ideas for erosion control I tested are using seaweed or a rock berm. I think the rock berm will work better than the model of seaweed because the seaweed is under water and the waves can carry the sand over the seaweed, and the rock berm will work better because the rocks will help break the waves up before they reach the shore and the waves can not carry the sand over the rocks that are above the water. To investigate this I got a container to use to model the Gulf of Mexico coastline. I performed several test runs using sand and water in the container to mimic the beach and waves from the Gulf of Mexico hitting the shoreline. I did three trials for the control (no erosion control), seaweed and a rock berm. Rock berms are a border of a raised area of rock. The model for seaweed that I used was plastic shopping bags cut into strips and glued to the bottom of my container to mimic seaweed. My results were that the control had the most erosion which ranged from 2.75 - 3 inches over 3 trials. The seaweed was a little better than the control but was very variable and ranged from 1.5 - 3 inches over 3 trials. The rock berm worked the best out of all at controlling erosion with erosion ranging from 1.5 - 2 inches. My hypothesis was correct because the rock berm did best to control erosion compared to the control which had no erosion control and the model with seaweed.

  13. Fissure sealant materials: Wear resistance of flowable composite resins.

    Science.gov (United States)

    Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

    2016-01-01

    Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm(2) and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm(2)of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  14. Standard test method for ranking resistance of plastics to sliding wear using block-on-ring wear test—cumulative wear method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This test method covers laboratory procedures for determining the resistance of plastics to sliding wear. The test utilizes a block-on-ring friction and wear testing machine to rank plastics according to their sliding wear characteristics against metals or other solids. 1.2 An important attribute of this test is that it is very flexible. Any material that can be fabricated into, or applied to, blocks and rings can be tested. Thus, the potential materials combinations are endless. In addition, the test can be run with different gaseous atmospheres and elevated temperatures, as desired, to simulate service conditions. 1.3 Wear test results are reported as the volume loss in cubic millimetres for the block and ring. Materials of higher wear resistance will have lower volume loss. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with it...

  15. Dental erosions and other extra-oesophageal symptoms of gastro-oesophageal reflux disease: Evidence, treatment response and areas of uncertainty.

    Science.gov (United States)

    Pauwels, Ans

    2015-04-01

    Extra-oesophageal symptoms of gastro-oesophageal reflux disease (GORD) are often studied, but remain a subject of debate. It has been clearly shown that there is a relationship between the extra-oesophageal symptoms chronic cough, asthma, laryngitis and dental erosion and GORD. Literature is abundant concerning reflux-related cough and reflux-related asthma, but much less is known about reflux-related dental erosions. The prevalence of dental erosion in GORD and vice versa, the prevalence of GORD in patients with dental erosion is high but the exact mechanism of reflux-induced tooth wear erosion is still under review.

  16. Changes in micro-relief during different water erosive stages of purple soil under simulated rainfall.

    Science.gov (United States)

    Luo, Jian; Zheng, Zicheng; Li, Tingxuan; He, Shuqin

    2018-02-22

    This study investigated the variation characteristics of micro-topography during successive erosive stages of water erosion: splash erosion (SpE), sheet erosion (ShE), and rill erosion (RE). Micro-topography was quantified using surface elevation change, soil roughness (SR) and multifractal model. Results showed that the area of soil surface elevation decay increased gradually with the development of water erosion. With rainfall, the combined effects of the detachment by raindrop impact and the transport of runoff decreased SR, whereas rill erosion contributed to increase SR. With the increase in slope gradient, soil erosion area gradually decreased at the splash erosion stage. By contrast, soil erosion area initially decreased and then increased at the sheet and rill erosion stages. The width of the D q spectra (ΔD) values increased at the splash erosion stage and then decreased at the sheet and rill erosion stages on the 10° slope, opposite to that on the 15° slope. The ΔD values decreased with the evolution of water erosive stages on the 20° slope. The slope had an enhancing effect on the evolution of water erosion. In this study, we clarified the essence of micro-topography and laid a theoretical foundation for further understanding diverse hydrological processes.

  17. Wear resistance of layers hard faced by the high-alloyed filler metal

    OpenAIRE

    Dušan Arsić; Vukić Lazić; Ruzica R. Nikolic; Milan Mutavdžić; Srbislav Aleksandrović; Milan Djordjević

    2016-01-01

    The objective of this work was to determine the wear resistance of layers hard faced by the high-alloyed filler metal, with or without the austenite inter-layer, on parts that operate at different sliding speeds in conditions without lubrication. The samples were hard faced with the filler metal E 10-UM-60-C with high content of C, Cr and W. Used filler metal belongs into group of alloys aimed for reparatory hard facing of parts damaged by abrasive and erosive wear and it is characterized by ...

  18. CFD Based Erosion Modelling of Abrasive Waterjet Nozzle using Discrete Phase Method

    International Nuclear Information System (INIS)

    Kamarudin, Naqib Hakim; Prasada Rao, A K; Azhari, Azmir

    2016-01-01

    In Abrasive Waterjet (AWJ) machining, the nozzle is the most critical component that influences the performance, precision and economy. Exposure to a high speed jet and abrasives makes it susceptible to wear erosion which requires for frequent replacement. The present works attempts to simulate the erosion of the nozzle wall using computational fluid dynamics. The erosion rate of the nozzle was simulated under different operating conditions. The simulation was carried out in several steps which is flow modelling, particle tracking and erosion rate calculation. Discrete Phase Method (DPM) and K-ε turbulence model was used for the simulation. Result shows that different operating conditions affect the erosion rate as well as the flow interaction of water, air and abrasives. The simulation results correlates well with past work. (paper)

  19. Statistical investigations into the erosion of material from the tool in micro-electrical discharge machining

    DEFF Research Database (Denmark)

    Puthumana, Govindan

    2018-01-01

    This paper presents a statistical study of the erosion of material from the tool electrode in a micro-electrical discharge machining process. The work involves analysis of variance and analysis of means approaches on the results of the tool electrode wear rate obtained based on design...... current (Id) and discharge frequency (fd) control the erosion of material from the tool electrode. The material erosion from the tool electrode (Me) increases linearly with the discharge frequency. As the current index increases from 20 to 35, the Me decreases linearly by 29%, and then increases by of 36......%. The current index of 35 gives the minimum material erosion from the tool. It is observed that none of the two-factor interactions are significant in controlling the erosion of the material from the tool....

  20. Erosion resistance and adhesion of composite metal/ceramic coatings produced by plasma spraying

    International Nuclear Information System (INIS)

    Ramm, D.A.J.; Hutchings, I.M.; Clyne, T.W.

    1993-01-01

    Ceramic coatings can exhibit greater erosion resistance than most metallic coatings. Such coatings are conveniently produced by thermal spraying. Unfortunately, thermally sprayed ceramic coatings often exhibit poor adhesion, partly as a consequence of the development of residual stresses during spraying and subsequent cooling. Composite coatings have been studied using aluminium/alumina deposits on steel substrates. The incorporation of ceramics within a ductile matrix has potential for sharply reducing the erosive wear at high erodent impact angles, whilst retaining the good erosion resistance of ceramics at low angles. It is shown that the proportion of metal and ceramic at the free surface can be specified so as to optimise the erosion resistance. Experiments have also been carried out on the resistance of the coatings to debonding during four-point bending of the coated substrate. Progress is being made towards the tailoring of composition profiles in graded coatings so as to optimise the combination of erosion resistance and adhesion. (orig.)

  1. Erosive Lichen Planus.

    Science.gov (United States)

    Mauskar, Melissa

    2017-09-01

    Lichen planus is an inflammatory mucocutaneous condition with a myriad of clinical manifestations. There are 3 forms of lichen planus that effect the vulva: papulosquamous, hypertrophic, and erosive. Erosive lichen planus can progress to vulvar scaring, vaginal stenosis, and squamous cell carcinoma; these long-term sequelae cause sexual distress, depression, and decreased quality of life for patients. Diagnosis is often delayed because of patient embarrassment or clinician misdiagnosis. Early recognition and treatment is essential to decreasing the morbidity of this condition. Multimodal treatment, along with a multidisciplinary approach, will improve outcomes and further clinical advances in studying this condition. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Assessment of mechanical and three-body abrasive wear peculiarity ...

    Indian Academy of Sciences (India)

    The three-body abrasive wear characteristic of fabricated composites has been assessed under different operating conditions. For this, the three-body abrasion test is done on dry abrasion test rig (TR-50)and analysed using Taguchi's experimental design scheme and analysis of variance. The results obtained from these ...

  3. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro; Ruggeri, Fabrizio; Tempone, Raul; Vilanova, Pedro

    2016-01-01

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  4. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro; Ruggeri, Fabrizio; Tempone, Raul; Vilanova, Pedro

    2015-01-01

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  5. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2015-01-07

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  6. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2014-01-06

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  7. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2016-01-06

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  8. Thin layer activation technique applied to the measurement of wear

    Energy Technology Data Exchange (ETDEWEB)

    Humphries, P [UKAEA Research Group, Harwell. Atomic Energy Research Establishment

    1978-01-01

    A thin layer of radioactive atoms is produced in the material by bombardment with charged particles, and as the material is worn away the total activity level is monitored. If the activity to depth relationship is then known the amount of material worn away can be determined. By a selective choice of the charged particle species and energy the depth of the active layer, its natural decay rate, and the energy of the emitted radiation can be pre-determined. The Harwell Tandem Electrostatic Generator has been found very suitable for the work. The total activity level can be made as little or as large as required, but a level around 5 to 10 microcuries is usually found to be adequate, and the active layer usually has a depth of 50 to 300 ..mu..m. The activated area can be from < 1 mm/sup 2/ to 4 cm/sup 2/. Particular reference is made to the production of /sup 56/Co in Fe. Experimental arrangements for the irradiation of components are described. Some practical applications undertaken by Harwell for industry are briefly mentioned, including wear of diesel engine valve seatings and fuel injection equipment, engine testing of lubricants, surface loss of rails and railway wheels, wear of gears, wear of graphite bearing materials, and corrosion and erosion of materials. 4 references.

  9. Mesh erosion after abdominal sacrocolpopexy.

    Science.gov (United States)

    Kohli, N; Walsh, P M; Roat, T W; Karram, M M

    1998-12-01

    To report our experience with erosion of permanent suture or mesh material after abdominal sacrocolpopexy. A retrospective chart review was performed to identify patients who underwent sacrocolpopexy by the same surgeon over 8 years. Demographic data, operative notes, hospital records, and office charts were reviewed after sacrocolpopexy. Patients with erosion of either suture or mesh were treated initially with conservative therapy followed by surgical intervention as required. Fifty-seven patients underwent sacrocolpopexy using synthetic mesh during the study period. The mean (range) postoperative follow-up was 19.9 (1.3-50) months. Seven patients (12%) had erosions after abdominal sacrocolpopexy with two suture erosions and five mesh erosions. Patients with suture erosion were asymptomatic compared with patients with mesh erosion, who presented with vaginal bleeding or discharge. The mean (+/-standard deviation) time to erosion was 14.0+/-7.7 (range 4-24) months. Both patients with suture erosion were treated conservatively with estrogen cream. All five patients with mesh erosion required transvaginal removal of the mesh. Mesh erosion can follow abdominal sacrocolpopexy over a long time, and usually presents as vaginal bleeding or discharge. Although patients with suture erosion can be managed successfully with conservative treatment, patients with mesh erosion require surgical intervention. Transvaginal removal of the mesh with vaginal advancement appears to be an effective treatment in patients failing conservative management.

  10. Wear of micro end mills

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2005-01-01

    This paper addresses the important issue of wear on micro end mills considering relevant metrological tools for its characterization and quantification. Investigation of wear on micro end mills is particularly difficult and no data are available in the literature. Small worn volumes cause large...... part. For this investigation 200 microns end mills are considered. Visual inspection of the micro tools requires high magnification and depth of focus. 3D reconstruction based on scanning electron microscope (SEM) images and stereo-pair technique is foreseen as a possible method for quantification...

  11. Calculation of wear (f.i. wear modulus) in the plastic cup of a hip joint prosthesis

    NARCIS (Netherlands)

    Ligterink, D.J.

    1975-01-01

    The wear equation is applied to the wear process in a hip joint prosthesis and a wear modulus is defined. The sliding distance, wear modulus, wear volume, wear area, contact angle and the maximum normal stress were calculated and the theoretical calculations applied to test results. During the wear

  12. Investigation of Erosion of Cement-Bentonite via Piping

    Directory of Open Access Journals (Sweden)

    Zijun Wang

    2017-01-01

    Full Text Available Cement-bentonite is one of the main materials used in the seepage barriers to protect earth dams and levees from water erosion. However, the current understanding of the erodibility of the cementitious materials and the interactions between cracked seepage barriers and the water flow is inadequate. Based on the laboratory pinhole erosion test, we first investigated the impacts of cement-bentonite treatments by using the ground granulated blast-furnace slag (GGBS as replacement on the erosion characteristics, compared with the original mixtures; the inclusion of GGBS highlighted a potential advantage against water erosion. In addition, we proposed to calculate the erosion percentage and establish the mathematical relationships between the erosion percentage and different regimes, that is, different curing period, erosion time, and sizes of initial holes. Results showed that enough curing period was critical to avoid the increases of hydraulic conductivity in the macrofabric of the barrier; meanwhile, the materials were eroded quickly at the beginning and slowed down with the erosion time, where the enlargement of the initial creaks would be stabilised at some point in time. Moreover, the sizes of initial holes may affect the erosion situation varying from the sample curing periods.

  13. [Research progress on wind erosion control with polyacrylamide (PAM).

    Science.gov (United States)

    Li, Yuan Yuan; Wang, Zhan Li

    2016-03-01

    Soil wind erosion is one of the main reasons for soil degradation in the northwest region of China. Polyacrylamide (PAM), as an efficient soil amendment, has gained extensive attention in recent years since it is effective in improving the structure of surface soil due to its special physical and chemical properties. This paper introduced the physical and chemical properties of PAM, reviewed the effects of PAM on soil wind erosion amount and threshold wind velocity, as well as the effect differences of PAM in soil wind erosion control under conditions of various methods and doses. Its effect was proved by comparing with other materials in detail. Furthermore, we analyzed the mecha-nism of wind erosion control with PAM according to its influence on soil physical characteristics. Comprehensive analysis showed that, although some problems existed in wind erosion control with (PAM), PAM as a sand fixation agent, can not only enhance the capacity of the soil resis-tance to wind erosion, but also improve soil physical properties to form better soil conditions. Besides, we proposed that combination of PAM and plant growth would increase the survival rate of plants greatly, control soil wind erosion in wind-erosive areas, and improve the quality of the ecological environment construction. Thus, PAM has practically important significance and wide application prospect in controlling soil wind erosion.

  14. Hybrid Composite Material and Solid Particle Erosion Studies

    Science.gov (United States)

    Chellaganesh, D.; Khan, M. Adam; Ashif, A. Mohamed; Ragul Selvan, T.; Nachiappan, S.; Winowlin Jappes, J. T.

    2018-04-01

    Composite is one of the predominant material for most challenging engineering components. Most of the components are in the place of automobile structure, aircraft structures, and wind turbine blade and so on. At the same all the components are indulged to mechanical loading. Recent research on composite material are machinability, wear, tear and corrosion studies. One of the major issue on recent research was solid particle air jet erosion. In this paper hybrid composite material with and without filler. The fibre are in the combination of hemp – kevlar (60:40 wt.%) as reinforcement using epoxy as a matrix. The natural material palm and coconut shell are used as filler materials in the form of crushed powder. The process parameter involved are air jet velocity, volume of erodent and angle of impingement. Experiment performed are in eight different combinations followed from 2k (k = 3) factorial design. From the investigation surface morphology was studied using electron microscope. Mass change with respect to time are used to calculate wear rate and the influence of the process parameters. While solid particle erosion the hard particle impregnates in soft matrix material. Influence of filler material has reduced the wear and compared to plain natural composite material.

  15. Direct restorative treatment of dental erosion caused by gastroesophageal reflux disease associated with bruxism: a case report

    OpenAIRE

    Vidal, Cristina de Mattos Pimenta [UNESP; Catelan, Anderson [UNESP; Briso, André Luiz Fraga [UNESP; Santos, Paulo Henrique dos [UNESP

    2011-01-01

    Gastroesophageal reflux disease (GERD) is a gastrointestinal disorder in which stomach acids are chronically regurgitated into the esophagus and oral cavity. Continual exposure of the teeth to these acids can cause severe tooth wear. Dentists are often the first healthcare professionals to diagnose dental erosion in patients with GERD. This article presents a case report of a 27-year-old male smoker with tooth wear and dentin sensitivity caused by GERD associated with bruxism. After diagnosis...

  16. Decontamination of radioactive contaminated protective wear using dry cleaning solvent

    International Nuclear Information System (INIS)

    Muthiah, Pushpa; Chitra, S.; Paul, Biplob

    2013-01-01

    Liquid waste generated by conventional decontamination of radioactive contaminated cotton protective wear using detergent affects the chemical treatment of the plant. To reduce the generation of aqueous detergent waste, dry cleaning of cotton protective wear, highly soiled with oil and grease towards decontamination was tried with organic solvents. Mineral turpentine oil (MTO) among various other organic solvents was identified as a suitable organic solvent. As MTO leaves characteristic odour on the cloth, various commercial fragrances for the removal of the odour were tried. Application of the optimised dry cleaning solvent and commercial fragrance was adopted in plant scale operation. (author)

  17. Erosion of dust aggregates

    NARCIS (Netherlands)

    Seizinger, A.; Krijt, S.; Kley, W.

    2013-01-01

    Aims: The aim of this work is to gain a deeper insight into how much different aggregate types are affected by erosion. Especially, it is important to study the influence of the velocity of the impacting projectiles. We also want to provide models for dust growth in protoplanetary disks with simple

  18. Hydrology and soil erosion

    Science.gov (United States)

    Leonard J. Lane; Mary R. Kidwell

    2003-01-01

    We review research on surface water hydrology and soil erosion at the Santa Rita Experimental Range (SRER). Almost all of the research was associated with eight small experimental watersheds established from 1974 to 1975 and operated until the present. Analysis of climatic features of the SRER supports extending research findings from the SRER to broad areas of the...

  19. Bentonite erosion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Martin; Boergesson, Lennart; Hedstroem, Magnus; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))

    2009-12-15

    Low saline water may reach KBS-3 repository depth, e.g. during periods of glaciation. Under such aqueous conditions, the montmorillonite part of the bentonite buffer might transform into a sol and thereby be transported away with flowing water in fractures. The primary aim with this report is to improve the understanding of the basic principles for this possible montmorillonite particle release. The report includes experimental and theoretical work performed at Clay Technology. Natural bentonite and ion-exchanged purified montmorillonite from three different geographical origins, Wyoming (U.S.), Milos (Greece) and Kutch (India) have been studied. Experimental and/or theoretical investigations have been performed with respect to: - Free swelling ability; - Rheological properties; - Rate of bentonite loss into fractures; - Filtering; - Ion exchange; - Sol formation ability; - Ion diffusion; - Mass loss due to erosion. The performed erosion experiments show that erosion does not occur in a mixed calcium/sodium montmorillonite with at least 20% calcium in exchange positions, when the external solution contains above 4 mM charge equivalents. This result is in agreement with the presented conceptual view of sol formation and measured equilibrium properties in mixed calcium/sodium montmorillonite. The findings imply that the buffer will be stable for non-glacial conditions. However, erosion due to sol formation cannot be ruled out for glacial conditions.

  20. Erosion scenarios for Wellenberg

    International Nuclear Information System (INIS)

    Klemenz, W.

    1993-09-01

    The proposed Wellenberg site for a radioactive waste repository is located between Altzellen in the Engelberger valley and the Oberrickenbach valley, in a thick Valanginian marl series. The marl is generally overlaid with unconsolidated rocks but reaches to the surface in some places. In contrast to the situation in the Oberbauenstock region this marl complex is not protected by an overlying erosion resistant series and exhibits a marked relief. The question therefore arises with respect to the Wellenberg site, to what extent will the marl (i.e. the repository host rock formation) be removed by erosion processes during the 100,000 years interval under consideration and what overburden will remain at the end of this period. This report presents the results of an investigation of the longterm behaviour of the proposed site in respect of those processes of erosion and deposition which can lead to changes in the terrain surface and its location relative to the repository. A wide range of possible scenarios encompassing different developments of climatic conditions during the 100,000 year period of interest, was investigated. In addition to the continuation of the present climate and the occurrence of a new ice age on the scale of the Wuerm glaciation the consequences of altered climatic conditions on erosion removal of the repository overburden were considered. Within the 100,000 year period of interest none of the scenarios considered leads to the exposure of the repository. (author) figs., tabs, refs

  1. Dune erosion above revetments

    NARCIS (Netherlands)

    Van Thiel de Vries, J.S.M.

    2012-01-01

    In a situation with a narrow dune, the dune base can be protected with a revetment to reduce dune erosion during extreme events. To quantify the effects of a revetment on storm impact, the functionality of the numerical storm impact model XBeach (Roelvink et al., 2009) is extended to account for the

  2. Bentonite erosion. Final report

    International Nuclear Information System (INIS)

    Birgersson, Martin; Boergesson, Lennart; Hedstroem, Magnus; Karnland, Ola; Nilsson, Ulf

    2009-12-01

    Low saline water may reach KBS-3 repository depth, e.g. during periods of glaciation. Under such aqueous conditions, the montmorillonite part of the bentonite buffer might transform into a sol and thereby be transported away with flowing water in fractures. The primary aim with this report is to improve the understanding of the basic principles for this possible montmorillonite particle release. The report includes experimental and theoretical work performed at Clay Technology. Natural bentonite and ion-exchanged purified montmorillonite from three different geographical origins, Wyoming (U.S.), Milos (Greece) and Kutch (India) have been studied. Experimental and/or theoretical investigations have been performed with respect to: - Free swelling ability; - Rheological properties; - Rate of bentonite loss into fractures; - Filtering; - Ion exchange; - Sol formation ability; - Ion diffusion; - Mass loss due to erosion. The performed erosion experiments show that erosion does not occur in a mixed calcium/sodium montmorillonite with at least 20% calcium in exchange positions, when the external solution contains above 4 mM charge equivalents. This result is in agreement with the presented conceptual view of sol formation and measured equilibrium properties in mixed calcium/sodium montmorillonite. The findings imply that the buffer will be stable for non-glacial conditions. However, erosion due to sol formation cannot be ruled out for glacial conditions.

  3. Soil erosion risk assessment using interviews, empirical soil erosion modeling (RUSLE) and fallout radionuclides in a volcanic crater lake watershed subjected to land use change, western Uganda

    Science.gov (United States)

    De Crop, Wannes; Ryken, Nick; Tomma Okuonzia, Judith; Van Ranst, Eric; Baert, Geert; Boeckx, Pascal; Verschuren, Dirk; Verdoodt, Ann

    2017-04-01

    Population pressure results in conversion of natural vegetation to cropland within the western Ugandan crater lake watersheds. These watersheds however are particularly prone to soil degradation and erosion because of the high rainfall intensity and steep topography. Increased soil erosion losses expose the aquatic ecosystems to excessive nutrient loading. In this study, the Katinda crater lake watershed, which is already heavily impacted by agricultural land use, was selected for an explorative study on its (top)soil characteristics - given the general lack of data on soils within these watersheds - as well as an assessment of soil erosion risks. Using group discussions and structured interviews, the local land users' perceptions on land use, soil quality, soil erosion and lake ecology were compiled. Datasets on rainfall, topsoil characteristics, slope gradient and length, and land use were collected. Subsequently a RUSLE erosion model was run. Results from this empirical erosion modeling approach were validated against soil erosion estimates based on 137Cs measurements.

  4. Categorization of erosion control matting.

    Science.gov (United States)

    2012-05-29

    Erosion control is a critical aspect of any Georgia Department of Transportation (GDOT) : construction project, with the extreme negative impacts of high sediment loads in natural : waterways having been well documented. A variety of erosion control ...

  5. Dental Erosion in Children with Gastroesophageal Reflux Disease.

    Science.gov (United States)

    De Oliveira, Patricia Alves Drummond; Paiva, Saul Martins; De Abreu, Mauro Henrique Nogueira Guimarães; Auad, Sheyla Márcia

    2016-01-01

    The purpose of this study was to investigate the impact of gastroesophageal reflux disease (GERD) on dental erosion (DE) in children and analyze the association between dental erosion and diet, oral hygiene, and sociodemographic characteristics. This case-control study encompassed 43 two- to 14-year-olds diagnosed positive for GERD by the 24-hour pH monitoring, paired by age group with 136 healthy controls, in Belo Horizonte, Minas Gerais, Brazil. DE was assessed by one calibrated examiner using the O'Sullivan index. A questionnaire was self-administered by parents collecting information regarding sociodemographics, oral hygiene, and dietary habits. Dental erosion experience was compared between the groups, and a stratified analysis was performed (PDental erosion was diagnosed in 10.6 percent (N equals 19) of all the children; 25.6 percent (N equals 11) of GERD children and 5.9 percent (N equals eight) of children without GERD, P=0.001). Dental erosion was not associated with dietary consumption or sociodemographic characteristics in both groups (P≥0.05). Children who used adult toothpaste had a 5.79 higher chance of having dental erosion in the group with GERD. Children diagnosed with gastroesophageal reflux disease were at an increased risk of having dental erosion when compared to healthy subjects; among the GERD children, dental erosion was associated with the use of adult toothpaste.

  6. Provision of wear resistance and fatigue strength of surfaces during electroerosive processing

    Science.gov (United States)

    Fedonin, O. N.; Syanov, S. Yu; Papikyan, A. M.

    2018-03-01

    This article is a generalization of the results of theoretical studies of the effect of erosion control regimes on the operational properties of mold-forming parts of molds. The main problem is the provision of wear resistance and fatigue strength in the electroerosion processing of these types of products. The analysis showed that the fatigue strength is affected by the processing regimes and the coefficient after the erosion treatment. The index of wear resistance is determined both by the treatment modes and by the physical-mechanical properties of the billet materials. To ensure the operational performance of products, it is necessary to establish the physical picture of the processing of complex profile parts by finding the optimum eroding regime.

  7. Three-dimensional in vitro measurements of tooth wear using fluoridated dentifrices.

    Science.gov (United States)

    Al-Mashhadani, A; Plygkos, I; Bozec, L; Rodriguez, J M

    2016-09-01

    The aim of this study was to compare differences in wear of human enamel and dentine in vitro using a 3D measurement method comparing silica versus non-silica containing fluoridated dentifrices (Colgate Total(™) [CT] or Fluor Protector Gel(™) [FPG]). Mounted native enamel (n = 36) and polished dentine (n = 36) samples were subjected to 10 wear cycles. Each cycle consisted of: (1) 1 hour remineralization in artificial saliva (AS); (2) 10 minute erosion (0.3% citric acid; pH = 2.8); (3) 2 minute toothbrush abrasion in AS (G1, control) or a slurry of 3:1 by weight of AS:dentifrice (G2 = CT; G3 = FPG) under a load of 2 N. Each group contained 12 enamel and 12 dentine samples. Paired pre- and post-wear scans made with a contacting scanner were digitally superimposed using ball bearings as datum. Mean and (SD) enamel wear was G1 = 21.9 μm (6.4); G2 = 15.2 μm (2.8); G3 = 16.9 μm (3.2). Enamel wear was not different between dentifrices (p = 0.99). Both dentifrices resulted in less enamel wear compared to the control (p Dental Association.

  8. Tooth wear risk assessment and care-planning in general dental practice.

    Science.gov (United States)

    O'Toole, S; Khan, M; Patel, A; Patel, N J; Shah, N; Bartlett, D; Movahedi, S

    2018-03-09

    Objective To assess charting, risk assessment and treatment-planning of tooth wear between recently qualified and experienced dentists in general dental practice.Design Service evaluation.Setting Multi-setting evaluation of three mixed NHS/Private general dental practices in North-East London.Methods The clinical notes of new patient examinations on dentate adults presenting from the 1 October 2016 to 31 December 2016 were audited collecting data on tooth wear charting, risk assessment and treatment planning. Data were analysed using descriptives, chi square and logistic regressions in SPSS. Significance was inferred at p charted for 48% of those attending foundation dentists and 5% of those attending experienced dentists. Diet was assessed in 50.6% of patients examined by foundation dentists and 1.0% of patients examined by experienced dentists. Foundation dentists were more likely to chart tooth wear, risk assess and preventively manage tooth wear compared to experienced dentists (p <0.001).Conclusion This service evaluation highlights that improvements are required in recording, risk assessing and preventive treatment planning of erosive tooth wear. Experienced dentists were less likely to risk assess tooth wear and less likely to provide preventive treatment. Experienced GDPs may benefit from re-training in this area.

  9. Wear resistance of layers hard faced by the high-alloyed filler metal

    Directory of Open Access Journals (Sweden)

    Dušan Arsić

    2016-10-01

    Full Text Available The objective of this work was to determine the wear resistance of layers hard faced by the high-alloyed filler metal, with or without the austenite inter-layer, on parts that operate at different sliding speeds in conditions without lubrication. The samples were hard faced with the filler metal E 10-UM-60-C with high content of C, Cr and W. Used filler metal belongs into group of alloys aimed for reparatory hard facing of parts damaged by abrasive and erosive wear and it is characterized by high hardness and wear resistance. In experiments, the sliding speed and the normal loading were varied and the wear scar was monitored, based on which the volume of the worn material was calculated analytically. The contact duration time was monitored over the sliding path of 300 mm. The most intensive wear was established for the loading force of 100 N and the sliding speed of 1 m.s-1, though the significant wear was also noticed in conditions of the small loading and speed of 0.25 m.s-1, which was even greater that at larger speeds.

  10. Friction and wear behavior of glasses and ceramics

    Science.gov (United States)

    Buckley, D. H.

    1973-01-01

    Adhesion, friction, and wear behavior of glasses and ionic solids are reviewed. These materials are shown to behave in a manner similar to other solids with respect to adhesion. Their friction characteristics are shown to be sensitive to environmental constituents and surface films. This sensitivity can be related to a reduction in adhesive bonding and the changes in surficial mechanical behavior associated with Rehbinder and Joffe effects. Both friction and wear properties of ionic crystalline solids are highly anisotropic. With metals in contact with ionic solids the fracture strength of the ionic solid and the shear strength in the metal and those properties that determine these will dictate which of the materials undergoes adhesive wear. The chemical activity of the metal plays an important role in the nature and strength of the adhesive interfacial bond that develops between the metal and a glass or ionic solid.

  11. A new production technique for wear resistant ring-hammers

    Directory of Open Access Journals (Sweden)

    Li Shifeng

    2011-11-01

    Full Text Available Based on a great number of laboratory experiments, a new technique has been developed for producing wear resistant ring-hammers. In this technology, lost foam casting with iron sand was combined to make mold; a special alloy was used to inoculate the molten steel, and proper heat treatment was used to further improve mechanical properties of wear resistant ring-hammers. The influence of this new production technology on the microstructure and mechanical properties of wear resistant ring-hammers was studied. Results show that iron sand molding, having the inherent characteristic of sand molding, changes the type of metallic compounds, refines crystal grains and increases the fineness of microstructure. Practical experience verified that the properties of the ring-hammers produced with this new technique are as follows: tensile strength (Rm 720 MPa, impact toughness (ak > 210 J•cm-2 and hardness > 200 HB. After water quenching from 1,080℃ (holding for 4 h and tempering at 320℃ for 3 h, the best wear resistance is obtained, and the wear resistance is 1.6 times higher than that of common high manganese ring-hammers.

  12. Should School Nurses Wear Uniforms?

    Science.gov (United States)

    Journal of School Health, 2001

    2001-01-01

    This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…

  13. Wear resistance of cast iron

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-10-01

    Full Text Available In this paper investigations of abrasive and adhesive wear resistance of different cast iron grades have been presented. Examinations showed, that the most advantageous pair of materials is the cast iron – the hardened steel with low-tempered martensite. It was found, that martensitic nodular cast iron with carbides is the most resistant material.

  14. An experimental study on the erosion behavior of pseudoelastic TiNi alloy in dry sand and in aggressive media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, T.; Li, D.Y. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical Engineering

    2000-11-30

    The corrosive erosion behavior of Ti-51at.%Ni alloy under different erosion conditions was studied and compared to that of 304 stainless steel. Erosion tests were performed in a slurry-pot tester with dry sand, 3.5% NaCl slurry and 0.1 moll{sup -1} H{sub 2}SO{sub 4} slurry containing 30% silica sand, respectively. Synergistic effects of corrosion and erosion were studied in steady corrosion, polarization, dry sand erosion and micro-wear experiments. An electrochemical-scratching test characterized the failure and recovery of the passive film formed on TiNi alloy in 3.5% NaCl and 0.1 mol l{sup -1} H{sub 2}SO{sub 4} solutions, respectively. In both dry sand and the corrosive media, the TiNi alloy exhibited considerably greater erosion resistance than 304 stainless steel. (orig.)

  15. Wear performance of laser processed tantalum coatings

    Energy Technology Data Exchange (ETDEWEB)

    Dittrick, Stanley; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit, E-mail: amitband@wsu.edu

    2011-12-01

    This first generation investigation evaluates the in vitro tribological performance of laser-processed Ta coatings on Ti for load-bearing implant applications. Linear reciprocating wear tests in simulated body fluid showed one order of magnitude less wear rate, of the order of 10{sup -4} mm{sup 3}(N.m){sup -1}, for Ta coatings compared to Ti. Our results demonstrate that Ta coatings can potentially minimize the early-stage bone-implant interface micro-motion induced wear debris generation due to their excellent bioactivity comparable to that of hydroxyapatite (HA), high wear resistance and toughness compared to popular HA coatings. Highlights: {yields} In vitro wear performance of laser processed Ta coatings on Ti was evaluated. {yields} Wear tests in SBF showed one order of magnitude less wear for Ta coatings than Ti. {yields} Ta coatings can minimize early-stage micro-motion induced wear debris generation.

  16. A study on mechanism of wear on body seat in nozzle of diesel fuel injector

    Energy Technology Data Exchange (ETDEWEB)

    Jeonggee, Son; Yamashita, Toru; Sato, Susumu; Kosaka, Hidenori; Masuko, Masabumi [Tokyo Institute of Technology (Japan)

    2013-06-01

    Wear of nozzle's body seat of diesel fuel injector, which is caused by the collision of needle on the body seat in a nozzle, affects fuel spray behaviors and injection characteristics. Recently, to reduce the wear of body seat, DLC nozzles are widely used. The DLC on the needle which is called diamond-like carbon has a certain effect in reducing wear of body seat. However, disallowable wear is reported at limited engine operating conditions. Moreover, the wear mechanism of body seat with DLC coated needle has not been made clear yet. In this study, the influence of temperature of the body seat and fuel property on the wear of DLC nozzle was investigated with a newly developed wear testing device which was constructed based on common-rail injection system. Worn surfaces of body seat were observed by FE-SEM, laser scanning microscope and EPMA. The obtained results from the measurements show that DLC nozzle has much less wear amount than non-DLC nozzle on the body seat and the corrosive wear effect is suppressed with DLC nozzle. (orig.)

  17. Dry Sliding Wear Behavior of Super Duplex Stainless Steel AISI 2507: a Statistical Approach

    Directory of Open Access Journals (Sweden)

    Davanageri M.

    2016-12-01

    Full Text Available The dry sliding wear behavior of heat-treated super duplex stainless steel AISI 2507 was examined by taking pin-on-disc type of wear-test rig. Independent parameters, namely applied load, sliding distance, and sliding speed, influence mainly the wear rate of super duplex stainless steel. The said material was heat treated to a temperature of 850°C for 1 hour followed by water quenching. The heat treatment was carried out to precipitate the secondary sigma phase formation. Experiments were conducted to study the influence of independent parameters set at three factor levels using the L27 orthogonal array of the Taguchi experimental design on the wear rate. Statistical significance of both individual and combined factor effects was determined for specific wear rate. Surface plots were drawn to explain the behavior of independent variables on the measured wear rate. Statistically, the models were validated using the analysis of variance test. Multiple non-linear regression equations were derived for wear rate expressed as non-linear functions of independent variables. Further, the prediction accuracy of the developed regression equation was tested with the actual experiments. The independent parameters responsible for the desired minimum wear rate were determined by using the desirability function approach. The worn-out surface characteristics obtained for the minimum wear rate was examined using the scanning electron microscope. The desired smooth surface was obtained for the determined optimal condition by desirability function approach.

  18. Gas Gun Studies of Interface Wear Effects

    Science.gov (United States)

    Jackson, Tyler; Kennedy, Greg; Thadhani, Naresh

    2011-06-01

    The characteristics of interface wear were studied by performing gas gun experiments at velocities up to 1 km/s. The approach involved developing coefficients of constitutive strength models for Al 6061 and OFHC-Cu, then using those to design die geometry for interface wear gas gun experiments. Taylor rod-on-anvil impact experiments were performed to obtain coefficients of the Johnson-Cook constitutive strength model by correlating experimentally obtained deformed states of impacted samples with those predicted using ANSYS AUTODYN hydrocode. Simulations were used with validated strength models to design geometry involving acceleration of Al rods through a copper concentric cylindrical angular extrusion die. Experiments were conducted using 7.62 mm and 80 mm diameter gas guns. Differences in the microstructure of the interface layer and microhardness values illustrate that stress-strain conditions produced during acceleration of Al through the hollow concentric copper die, at velocities less than 800 m/s, result in formation of a layer via solid state alloying due to severe plastic deformation, while higher velocities produce an interface layer consisting of melted and re-solidified aluminum.

  19. Measurement of Wear in Radial Journal Bearings

    NARCIS (Netherlands)

    Ligterink, D.J.; Ligterink, D.J.; de Gee, A.W.J.

    1996-01-01

    this article, the measurement of wear in radial journal bearings is discussed, where a distinction is made between stationary and non-stationary contact conditions. Starting with Holm/Archard's wear law, equations are derived for the calculation of the specific wear rate k of the bearing material as

  20. Backside wear in modern total knee designs.

    Science.gov (United States)

    Jayabalan, Prakash; Furman, Bridgette D; Cottrell, Jocelyn M; Wright, Timothy M

    2007-02-01

    Although modularity affords various options to the orthopedic surgeon, these benefits come at a price. The unintended bearing surface between the back surface of the tibial insert and the metallic tray results in micromotion leading to polyethylene wear debris. The objective of this study was to examine the backside wear of tibial inserts from three modern total knee designs with very different locking mechanisms: Insall-Burstein II (IB II), Optetrak, and Advance. A random sample of 71 inserts were obtained from our institution's retrieval collection and examined to assess the extent of wear, depth of wear, and wear damage modes. Patient records were also obtained to determine patient age, body mass index, length of implantation, and reason for revision. Modes of wear damage (abrasion, burnishing, scratching, delamination, third body debris, surface deformation, and pitting) were then scored in each zone from 0 to 3 (0 = 0%, 1 = 0-10%, 2 = 10-50%, and 3 = >50%). The depth of wear was subjectively identified as removal of manufacturing identification markings stamped onto the inferior surface of the polyethylene. Both Advance and IB II polyethylene inserts showed significantly higher scores for backside wear than the Optetrak inserts. All IB II and Advance implants showed evidence of backside wear, whereas 17% (5 out of 30) of the retrieved Optetrak implants had no observable wear. There were no significant differences when comparing the depth of wear score between designs. The locking mechanism greatly affects the propensity for wear and should be considered when choosing a knee implant system.

  1. Microstructure, Wear Behavior and Corrosion Resistance of WC-FeCrAl and WC-WB-Co Coatings

    Directory of Open Access Journals (Sweden)

    Janette Brezinová

    2018-05-01

    Full Text Available The paper is focused on investigating the quality of two grades of thermally sprayed coatings deposited by high-velocity oxygen fuel (HVOF technology. One grade contains WC hard particles in an environmentally progressive Ni- and Co-free FeCrAl matrix, while the second coating contains WC and WB hard particles in a cobalt matrix. The aim of the experimental work was to determine the effect of thermal cyclic loading on the coatings’ resistance to adhesive, abrasive and erosive wear. Abrasive wear was evaluated using abrasive cloth of two grit sizes, and erosive wear was evaluated by a dry-pot wear test in a pin mill at two sample angles. Adhesion wear resistance of the coatings was determined by a sliding wear test under dry friction conditions and in a 1 mol water solution of NaCl. Corrosion resistance of the coatings was evaluated using potentiodynamic polarization tests. Metallographic cross-sections were used for measurement of the microhardness and thickness and for line energy-dispersive X-ray (EDX analysis. The tests proved the excellent resistance of both coatings against adhesive, abrasive, and erosive wear, as well as the ability of the WC-WB-Co coating to withstand alternating temperatures of up to 600 °C. The “green carbide” coating (WC-FeCrAl can be recommended as an environmentally friendly replacement for Ni- and Co-containing coatings, but its operating temperature is strictly limited to 500 °C in air.

  2. Torrent classification - Base of rational management of erosive regions

    International Nuclear Information System (INIS)

    Gavrilovic, Zoran; Stefanovic, Milutin; Milovanovic, Irina; Cotric, Jelena; Milojevic, Mileta

    2008-01-01

    A complex methodology for torrents and erosion and the associated calculations was developed during the second half of the twentieth century in Serbia. It was the 'Erosion Potential Method'. One of the modules of that complex method was focused on torrent classification. The module enables the identification of hydro graphic, climate and erosion characteristics. The method makes it possible for each torrent, regardless of its magnitude, to be simply and recognizably described by the 'Formula of torrentially'. The above torrent classification is the base on which a set of optimisation calculations is developed for the required scope of erosion-control works and measures, the application of which enables the management of significantly larger erosion and torrential regions compared to the previous period. This paper will present the procedure and the method of torrent classification.

  3. Torrent classification - Base of rational management of erosive regions

    Energy Technology Data Exchange (ETDEWEB)

    Gavrilovic, Zoran; Stefanovic, Milutin; Milovanovic, Irina; Cotric, Jelena; Milojevic, Mileta [Institute for the Development of Water Resources ' Jaroslav Cerni' , 11226 Beograd (Pinosava), Jaroslava Cernog 80 (Serbia)], E-mail: gavrilovicz@sbb.rs

    2008-11-01

    A complex methodology for torrents and erosion and the associated calculations was developed during the second half of the twentieth century in Serbia. It was the 'Erosion Potential Method'. One of the modules of that complex method was focused on torrent classification. The module enables the identification of hydro graphic, climate and erosion characteristics. The method makes it possible for each torrent, regardless of its magnitude, to be simply and recognizably described by the 'Formula of torrentially'. The above torrent classification is the base on which a set of optimisation calculations is developed for the required scope of erosion-control works and measures, the application of which enables the management of significantly larger erosion and torrential regions compared to the previous period. This paper will present the procedure and the method of torrent classification.

  4. Assessment of wear dependence parameters in complex model of cutting tool wear

    Science.gov (United States)

    Antsev, A. V.; Pasko, N. I.; Antseva, N. V.

    2018-03-01

    This paper addresses wear dependence of the generic efficient life period of cutting tools taken as an aggregate of the law of tool wear rate distribution and dependence of parameters of this law's on the cutting mode, factoring in the random factor as exemplified by the complex model of wear. The complex model of wear takes into account the variance of cutting properties within one batch of tools, variance in machinability within one batch of workpieces, and the stochastic nature of the wear process itself. A technique of assessment of wear dependence parameters in a complex model of cutting tool wear is provided. The technique is supported by a numerical example.

  5. Prevalence of dental erosion among people with gastroesophageal reflux disease in China.

    Science.gov (United States)

    Li, Wenhao; Liu, Jingming; Chen, Su; Wang, Yao; Zhang, Zhenting

    2017-01-01

    Gastroesophageal reflux disease (GERD) is typically diagnosed based on symptoms of regurgitation and heartburn, although it may also manifest as asthma-like symptoms, laryngitis, or dental erosion. The purpose of this prospective, cross-sectional study was to assess the prevalence of dental erosion in people with GERD and to evaluate the association between GERD and dental erosion. The presence, severity, and pattern of dental erosion was assessed in 51 participants with GERD and 50 participants without GERD using the Smith and Knight tooth wear index. Medical, dietary, and dental histories were collected by questionnaire. Factors potentially related to dental erosion, including GERD, were evaluated by logistic regression. Dental erosion was observed in 31 (60.8%) participants with GERD and 14 (28%) participants without GERD. Bivariate analysis revealed that participants with GERD were more likely to experience dental erosion (crude odds ratio [cOR]: 2.74; 95% CI: 1.19, 6.32) than participants without GERD. Multivariate analysis also revealed that participants with GERD had a higher risk of dental erosion (adjusted odds ratio [aOR]: 3.97; 95% CI: 1.45, 10.89). Consumption of grains and legumes, the most frequently consumed foods in China, did not correlate with dental erosion. However, carbonated beverage consumption was significantly associated with GERD and dental erosion (aOR: 3.34; 95% CI: 1.01, 11.04; P=.04). GERD was positively correlated with dental erosion. Carbonated beverage consumption can increase the risk of both GERD and dental erosion. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  6. Rainfall erosivity map for Ghana

    International Nuclear Information System (INIS)

    Oduro Afriyie, K.

    1995-10-01

    Monthly rainfall data, spanning over a period of more than thirty years, were used to compute rainfall erosivity indices for various stations in Ghana, using the Fournier index, c, defined as p 2 /P, where p is the rainfall amount in the wettest month and P is the annual rainfall amount. Values of the rainfall erosivity indices ranged from 24.5 mm at Sunyani in the mid-portion of Ghana to 180.9 mm at Axim in the south western coastal portion. The indices were used to construct a rainfall erosivity map for the country. The map revealed that Ghana may be broadly divided into five major erosion risk zones. The middle sector of Ghana is generally in the low erosion risk zone; the northern sector is in the moderate to severe erosion risk zone, while the coastal sector is in the severe to extreme severe erosion risk zone. (author). 11 refs, 1 fig., 1 tab

  7. Simplified analytical modeling of the normal hole erosion test; Modelado analitico simplificado del ensayo normal de ersoion de tubo

    Energy Technology Data Exchange (ETDEWEB)

    Khamlichi, A.; Bezzazi, M.; El Bakkali, L.; Jabbouri, A.; Kissi, B.; Yakhlef, F.; Parron Vera, M. A.; Rubio Cintas, M. D.; Castillo Lopez, O.

    2009-07-01

    The role erosion test was developed in order to study erosion phenomenon which occurs in cracks appearing in hydraulic infrastructures such as dams. This test enables describing experimentally the erosive characteristics of soils by means of an index which is called erosion rate and a critical tension which indicates the threshold of surface erosion initiation. The objective of this work is to five modelling of this experiment by means of a simplified analytical approach. The erosion law is derived by taking into account the flow regime. This law shows that the erosion occurring in the tube is controlled by a first order dynamics where only two parameters are involved: the characteristic's time linked to the erosion rate and the stress shear threshold for which erosion begins to develop. (Author) 5 refs.

  8. Influence of nitrogen ion implantation on wear studied by a new laboratory wear test

    Energy Technology Data Exchange (ETDEWEB)

    Szilagyi, E.; Paszti, F.; Vertessy, Z. (Central Research Inst. for Physics, Hungarian Academy of Sciences, Budapest (Hungary))

    1991-05-01

    A new laboratory wear test is developed in which the wear trace is measured by Rutherford backscattering spectrometry. The advantage of the new test is that the wear rate is directly determinable. The new test setup has been used to study the effects of nitrogen implantation on the wear processes on 115CrV3 steel. The wear rate decreases by a factor of 2 at 4x10{sup 17} N{sup +}/cm{sup 2} implanted dose. (orig.).

  9. Scoping erosion flow loop test results in support of Hanford WTP

    International Nuclear Information System (INIS)

    Duignan, M.; Imrich, K.; Fowley, M.; Restivo, M.; Reigel, M.

    2015-01-01

    The Waste Treatment and Immobilization Plant (WTP) will process Hanford Site tank waste by converting the waste into a stable glass form. Before the tank waste can be vitrified, the baseline plan is to process the waste through the Pretreatment (PT) Facility where it will be mixed in various process vessels using Pulse Jet Mixers (PJM) and transferred to the High Level Waste (HLW) or Low Activity Waste (LAW) vitrification facilities. The Department of Energy (DOE) and Defense Nuclear Facility Safety Board (DNFSB), as well as independent review groups, have raised concerns regarding the design basis for piping erosion in the PT Facility. Due to the complex nature of slurry erosion/corrosion wear and the unique conditions that exist within the PT Facility, additional testing has been recommended by these entities. Pipe loop testing is necessary to analyze the potential for localized wear at elbows and bends, close the outstanding PT and HLW erosion/corrosion technical issues, and underpin BNI's design basis for a 40-year operational life for black cell piping and vessels. SRNL is consulting with the DOE Office of River Protection (ORP) to resolve technical concerns related to piping erosion/corrosion (wear) design basis for PT. SRNL was tasked by ORP to start designing, building, and testing a flow loop to obtain long-term total-wear rate data using bounding simulant chemistry, operating conditions, and prototypical materials. The initial test involved a scoping paint loop to locate experimentally the potential high-wear locations. This information will provide a basis for the placement of the many sensitive wear measurement instruments in the appropriate locations so that the principal flow-loop test has the best chance to estimate long-term erosion and corrosion. It is important to note that the scoping paint loop test only utilized a bounding erosion simulant for this test. A full chemical simulant needs to be added for the complete test flow loop. The

  10. New methodology for fast prediction of wheel wear evolution

    Science.gov (United States)

    Apezetxea, I. S.; Perez, X.; Casanueva, C.; Alonso, A.

    2017-07-01

    In railway applications wear prediction in the wheel-rail interface is a fundamental matter in order to study problems such as wheel lifespan and the evolution of vehicle dynamic characteristic with time. However, one of the principal drawbacks of the existing methodologies for calculating the wear evolution is the computational cost. This paper proposes a new wear prediction methodology with a reduced computational cost. This methodology is based on two main steps: the first one is the substitution of the calculations over the whole network by the calculation of the contact conditions in certain characteristic point from whose result the wheel wear evolution can be inferred. The second one is the substitution of the dynamic calculation (time integration calculations) by the quasi-static calculation (the solution of the quasi-static situation of a vehicle at a certain point which is the same that neglecting the acceleration terms in the dynamic equations). These simplifications allow a significant reduction of computational cost to be obtained while maintaining an acceptable level of accuracy (error order of 5-10%). Several case studies are analysed along the paper with the objective of assessing the proposed methodology. The results obtained in the case studies allow concluding that the proposed methodology is valid for an arbitrary vehicle running through an arbitrary track layout.

  11. Friction and wear in sodium

    International Nuclear Information System (INIS)

    Hoffman, N.J.; Droher, J.J.

    1973-01-01

    In the design of a safe and reliable sodium-cooled reactor one of the more important problem areas is that of friction and wear of components immersed in liquid sodium or exposed to sodium vapor. Sodium coolant at elevated temperatures may severely affect most oxide-bearing surface layers which provide corrosion resistance and, to some extent, lubrication and surface hardness. Consequently, accelerated deterioration may be experienced on engaged-motion contact surfaces, which could result in unexpected reactor shutdown from component malfunction or failure due to galling and seizure. An overall view of the friction and wear phenomena encountered during oscillatory rubbing of surfaces in high-temperature, liquid-sodium environments is presented. Specific data generated at the Liquid Metal Engineering Center (LMEC) on this subject is also presented. (U.S.)

  12. Dental erosion in 12-year-old school children living in Jakarta

    Science.gov (United States)

    Septalita, A.; Bahar, A.; Agustanti, A.; Rahardjo, A.; Maharani, D. A.; Rosalien, R.

    2017-08-01

    This study assesses the dental erosion status of 12-year-old Indonesian children and studies the determinants of dental erosion of these children. The survey was performed in 2016 with ethics approval. A multistage cluster proportional to size random sampling method was adopted to select 12-year-old children in 24 primary schools in Jakarta. The parents were asked to complete a self-administered questionnaire concerning their children’s diet and oral health habits. The children were examined by a single calibrated examiner. Detection of dental erosion followed basic erosive wear examination (BEWE) criteria. A total of 487 children participated in the survey. Most children (88%) had at least some signs of erosion (BEWE > 0), with dentin being involved in 50% of the cases (BEWE = 2). Dental erosion was significantly related to gender, the frequencies of citric tea consumption, parent’s dental knowledge, father’s education, and dental caries (OR = 3.148). The 12-year-old Indonesian school children who lived in Jakarta had signs of erosion, although severe erosion was not found. Screening programs should be provided to identify risk groups so early preventive measures can be taken.

  13. Dental erosion prevalence and associated risk indicators among preschool children in Athens, Greece.

    Science.gov (United States)

    Mantonanaki, Magdalini; Koletsi-Kounari, Haroula; Mamai-Homata, Eleni; Papaioannou, William

    2013-03-01

    The aims of the study were to investigate dental erosion prevalence, distribution and severity in Greek preschool children attending public kindergartens in the prefecture of Attica, Greece and to determine the effect of dental caries, oral hygiene level, socio-economic factors, dental behavior, erosion related medication and chronic illness. A random and stratified sample of 605 Greek preschool children was clinically examined for dental erosion using the Basic Erosive Wear Examination Index (ΒΕWE). Dental caries (dmfs) and Simplified Debris Index were also recorded. The data concerning possible risk indicators were derived by a questionnaire. Zero-inflated Poisson regression was generated to test the predictive effects of the independent variables on dental erosion. The prevalence of dental erosion was 78.8 %, and the mean and SE of BEWE index was 3.64 ± 0.15. High monthly family income was positively related to ΒΕWE cumulative scores [RR = 1.204 (1.016-1.427)], while high maternal education level [RR = 0.872 (0.771-0.986)] and poor oral hygiene level [DI-s, RR = 0.584 (0.450-0.756)] showed a negative association. Dental erosion is a common oral disease in Greek preschool children in Attica, related to oral hygiene and socio-economic factors. Programs aimed at erosion prevention should begin at an early age for all children.

  14. Wear of rolling element bearings in sodium

    International Nuclear Information System (INIS)

    Campbell, C.S.

    1976-01-01

    Rolling element bearings and related mechanisms are attractive for service in liquid sodium but it is not clear what minimum wear rate can be anticipated. For axially loaded angular contact bearings rotation is incompatible with pure rolling on both races and wear arises from the resulting ball spin. The initial pressure distributions and sizes of the contact ellipses can be calculated but will change with bearing wear. However, the most effective distribution for producing wear would be for the full loads to be borne on the tips of the contact areas, whose maximum length is given by examination of the race wear tracks. A calculation on such a basis should set a lower limit for the wear coefficient. Both the torque and instantaneous wear rate of a bearing will be similar functions of the integral over the contact areas of the product of contact pressure and radius from the ball spin axis. A better estimate of wear coefficient should be obtained by relating the average torque, the average wear, the initial torque and the initial wear where the conditions are known. Analysis of tests in sodium at 400 0 C of high speed steel and Stellite bearings by these methods indicates specific wear rates of the order of 10 -15 m 3 /N-m, not unduly out of line with the range of values found in conventional sliding tests

  15. Fluoridation and tooth wear in Irish adults.

    LENUS (Irish Health Repository)

    Burke, F M

    2010-10-01

    The aim of this study was to determine the prevalence of tooth wear in adults in Ireland and its relationship with water fluoridation. The National Survey of Adult Oral Health was conducted in 2000\\/2001. Tooth wear was determined using a partial mouth examination assessing the upper and lower anterior teeth. A total of 2456 subjects were examined. In this survey, increasing levels and severity of tooth wear were associated with ageing. Men were more affected by tooth wear and were more likely to be affected by severe tooth wear than women. It was found that age, and gender were significant predictors of tooth wear (P < 0.01). Overall, there was no significant relationship between fluoridation and tooth wear in this study.

  16. A new mathematical model of the surface degradation causing wear on the cutting tool`s flank land

    OpenAIRE

    Pаlmai, Z.

    2011-01-01

    Having reviewed the extensive literature on the wear of the cutting tool, we chose the theoretical description of flank wear as the subject matter of this paper. Based on the optical electron-optical and morphological studies of the physical characteristics of wear processes we came to the conclusion that the cutting distance need not only be taken into consideration in abrasive, adhesive processes but also in thermally activated diffusion, oxidation processes. Consequently, we propose the ap...

  17. Erosion-corrosion synergistics in the low erosion regime

    International Nuclear Information System (INIS)

    Corey, R.G.; Sethi, V.K.

    1986-01-01

    Many engineering alloys display good high temperature corrosion resistance. However, when they are used in corrosive environments where they are subjected to erosion also, the corrosion resistance has been adversely affected. The phenomenon known as erosion-corrosion is complex and requires detailed investigation of how the erosion and corrosion kinetics interact and compete. At the Kentucky Center for Energy Research Laboratory, an erosion-corrosion tester was used to perform erosion-oxidation tests on 2 1/4 Cr-1 Mo steel at 500-600 0 C using alumina abrasive at low velocities. The erosion-oxidation rate data and morphology of exposed surfaces are consistent with oxide chipping and fracturing being the mode of material loss

  18. New approaches to the estimation of erosion-corrosion

    International Nuclear Information System (INIS)

    Bakirov, Murat; Ereemin, Alexandr; Levchuck, Vasiliy; Chubarov, Sergey

    2006-09-01

    erosion-corrosion in a double-phase flow is that of moving deaerated liquid in directly contact with metal as a barrier between the metal and main steam-drop flow. Local processes of mass transfer, corrosion properties and water-chemical parameters of this film define intensity of erosion-corrosion and features of its behavior. Erosion-corrosion of metal in a double-phase flow is determined by the gas-dynamics of double-phase flaws, water chemistry, thermodynamic, materials science, etc. The goal of the work: development of theoretical and methodological basis of physical, chemical and mathematical models, as well as the finding of technical solutions and method of diagnostics, forecast and control of the erosion-corrosion processes. It will allow the increase of reliability and safety operation of the power equipment of the secondary circuit in NPP with WWER by use of monitoring of erosion-corrosion wear of pipelines. One concludes by stressing that the described design-experimental approach for solving of FAC problem will enable to carry out the following works: - elaboration and certification of the procedure of design-experimental substantiation of zones, aims and periodicity of the NPP elements operational inspection; - development and certification of a new Regulatory Document of stress calculation for definition of the minimum acceptable wall thickness levels considering real wear shape, FAC rates and inaccuracy of devices for wall thickness measurements; - improving the current Regulatory Documents and correcting of the Typical programs of operational inspection - optimization of zones, aims and periodicity of the inspection; - elaboration of recommendations for operational lifetime prolongation of the WWER secondary circuits elements by means of increasing of erosion-corrosion resistance of the new equipment and of the equipment, exceeding the design lifetime; - improving of safe and uninterrupted work of the power unit due to prediction of the most damaged

  19. Study of alternative materials to minimize erosion in heat exchanger tubes used in thermoelectric generators

    Energy Technology Data Exchange (ETDEWEB)

    Arnt, A.B.C.; Paula, M.M. da S. Paula; Rocha, M.R. da; Angioletto, E.; Zanini, L.C.; Miranda, R.; Zanelatto, C.C. [Universidade do Extremo Sul Catarinense (UNESC), Criciuma, SC (Brazil)], e-mails: anb@unesc.net, mms@unesc.net, marcio2r@terra.com.br, an@unesc.net, elucaslcz@yahoo.com.br, frdgmiranda@hotmail.com, gcrisrincao20@yahoo.com.br; Felippe, L. [Universidade do Extremo Sul Catarinense (UNESC), Capivari de Baixo, SC (Brazil)], e-mail: hlfelippe@tractebelenergia.com.br

    2007-07-01

    The machinery used in coal thermo electrical plants usually is submitted to erosive wear. The erosive wear occurs mainly in the metallic pipe set of heat exchangers due the flow of hot gases carrying erosive particles. Jaguar Ludicrous thermo electrical complex at Capivari de Baixo city holds seven power units, where two units use approximately 20 000 ASTM A178 heat pipes. The set is submitted to a semester maintenance schedule (preventive and corrective) where the damaged pipes are changed. So, in this work a set of erosive wear accelerated tests according ASTM G76 were performed in order to develop and specify materials and methods to diminish the erosive action caused by the combustion gases over the heat pipes. Specimens were coated with WC12Co and Cr{sub 3}C{sub 2}-25NiCr alloys using the HVOF technique and the coated specimens were tested at 450 deg C, the heat pipes working temperature. Silica was used as abrasive material at 30 deg and 45 deg impact angles, simulating a harder erosive condition than the real condition. The best performance coating at laboratory scale was later used in field condition. The results showed the coated specimen performance is better than the ASTM A178 alloy. The erosion resistance of the Cr{sub 3}C{sub 2}-25NiCr and WC12Co coatings is eight times higher than the uncoated alloy, and the coatings also presented a better corrosion resistance. This feature is important, because despite the erosive action the circulating gases also present a large amount of sulfur in their composition. Sulfur at lower temperatures forms H{sub 2}SO{sub 4}, causing intense corrosion of the pipes located at the heat exchangers colder parts. Based on the results and considering the coating costs the Cr{sub 3}C{sub 2}-25NiCr alloy was selected to coat a set of pipes mounted at the region of the heat exchanger with the most intense erosive wear. At the moment these coated tubes are in field operation and under observation regarding their performance in

  20. Wear behavior of Al-7%Si-0.3%Mg/melon shell ash particulate composites.

    Science.gov (United States)

    Abdulwahab, M; Dodo, R M; Suleiman, I Y; Gebi, A I; Umar, I

    2017-08-01

    The present study examined wear characteristics of A356/melon shell ash particulate composites. Dry-sliding the stainless steel ball against specimen disc revealed the abrasive wear behavior of the composites under loads of 2 and 5N. The composite showed lower wear rate of 2.182 × 10 -4 mm 3 /Nm at 20 wt% reinforced material under load of 5N. Results showed that wear rate decreased significantly with increasing weight percentage of melon shell ash particles. Microstructural analyses of worn surfaces of the composites reveal evidence of plastic deformation of matrix phase. The wear resistance of A356 increased considerably with percentage reinforcement. In other words, the abrasive mass loss decreased with increasing percentage of reinforcement addition at the both applied loads. The control sample suffered a highest mass loss at 5 N applied load.

  1. Wear and creep of highly crosslinked polyethylene against cobalt chrome and ceramic femoral heads.

    Science.gov (United States)

    Galvin, A L; Jennings, L M; Tipper, J L; Ingham, E; Fisher, J

    2010-10-01

    The wear and creep characteristics of highly crosslinked ultrahigh-molecular-weight polyethylene (UHMWPE) articulating against large-diameter (36mm) ceramic and cobalt chrome femoral heads have been investigated in a physiological anatomical hip joint simulator for 10 million cycles. The crosslinked UHMWPE/ceramic combination showed higher volume deformation due to creep plus wear during the first 2 million cycles, and a steady-state wear rate 40 per cent lower than that of the crosslinked UHMWPE/cobalt chrome combination. Wear particles were isolated and characterized from the hip simulator lubricants. The wear particles were similar in size and morphology for both head materials. The particle isolation methodology used could not detect a statistically significant difference between the particles produced by the cobalt chrome and alumina ceramic femoral heads.

  2. Wear Behavior of Selected Nuclear Grade Graphites at Room Temperature in Ambient Air Environment

    International Nuclear Information System (INIS)

    Kim, Eung-Seon; Park, Kwang-Seok; Kim, Yong-Wan

    2008-01-01

    In a very high temperature reactor (VHTR), graphite will be used not only for as a moderator and reflector but also as a major structural component due to its excellent neutronic, thermal and mechanical properties. In the VHTR, wear of graphite components is inevitable due to a neutron irradiation-induced dimensional change, thermal gradient, relative motions of graphite components and a shock load such as an earthquake. Large wear particles accumulated at the bottom of a reactor can influence the cooling of the lower part and small wear particles accumulated on the primary circuit and heat exchanger tube can make it difficult to inspect the equipment, and also decrease the heat exchange rate. In the present work, preliminary wear tests were performed at room temperature in ambient air environment to understand the basic wear characteristics of selected nuclear grade graphites for the VHTR

  3. Soil erosion in Iran: Issues and solutions

    Science.gov (United States)

    Hamidreza Sadeghi, Seyed; Cerdà, Artemi

    2015-04-01

    Iran currently faces many soil erosion-related problems (see citations below). These issues are resulted from some inherent characteristic and anthropogenic triggering forces. Nowadays, the latter plays more important rule to accelerate the erosion with further emphasis on soil erosion-prone arid and semi arid regions of the country. This contribution attempts to identify and describe the existing main reasons behind accelerated soil erosion in Iran. Appropriate solutions viz. structural and non-structural approaches will be then advised to combat or minimise the problems. Iran can be used as a pilot research site to understand the soil erosion processes in semiarid, arid and mountainous terrain and our research will review the scientific literature and will give an insight of the soil erosion rates in the main factors of the soil erosion in Iran. Key words: Anthropogenic Erosion, Land Degradation; Sediment Management; Sediment Problems Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and PREVENTING AND REMEDIATING DEGRADATION OF SOILS IN EUROPE THROUGH LAND CARE (RECARE)FP7-ENV-2013- supported this research. References Aghili Nategh, N., Hemmat, A., & Sadeghi, M. (2014). Assessing confined and semi-confined compression curves of highly calcareous remolded soil amended with farmyard manure. Journal of Terramechanics, 53, 75-82. Arekhi, S., Bolourani, A. D., Shabani, A., Fathizad, H., Ahamdy-Asbchin, S. 2012. Mapping Soil Erosion and Sediment Yield Susceptibility using RUSLE, Remote Sensing and GIS (Case study: Cham Gardalan Watershed, Iran). Advances in Environmental Biology, 6(1), 109-124. Arekhi, S., Shabani, A., Rostamizad, G. 2012. Application of the modified universal soil loss equation (MUSLE) in prediction of sediment yield (Case study: Kengir Watershed, Iran). Arabian Journal of Geosciences, 5(6), 1259-1267.Sadeghi, S. H., Moosavi, V., Karami, A., Behnia, N. 2012. Soil erosion assessment and prioritization of affecting factors at plot

  4. A terminological matter: paragenesis, antigravitative erosion or antigravitational erosion ?

    Directory of Open Access Journals (Sweden)

    Pasini G.

    2009-07-01

    Full Text Available In the speleological literature three terms are utilized to designate the “ascending erosion”: paragenesis (= paragénésis, coined in1968, antigravitative erosion (= erosione antigravitativa, coined in 1966 and antigravitational erosion (wrong English translation ofthe Italian term erosione antigravitativa, utilized later on. The term paragenesis should be abandoned because of the priority of theterm erosione antigravitativa - on the ground of the “law of priority” – and because of its ambiguous etimology. On the other hand,the term antigravitational erosion should be forsaken in favour of the term antigravitative erosion, given the meaning that the termsgravitation and gravity have in Physics. Therefore, to designate the phenomenon of the “ascending erosion” there would be nothingleft but the term antigravitative erosion.The antigravitative erosion process and its recognizability are illustrated.Examples of caves with evident antigravitative erosion phenomena, developed in different karstifiable rocks and in several partsof the world, are given.It is recalled that the antigravitative erosion is a phenomenon well-known since 1942 and widely proven and supported, and that it isrelatively easy – in many cases - to recognize the antigravitative origin of karstic passages.It is stressed that the antigravitative erosion is an important phenomenon, exclusive of the karstic caves and unique in nature.

  5. Laser speckle imaging: a novel method for detecting dental erosion.

    Directory of Open Access Journals (Sweden)

    Nelson H Koshoji

    Full Text Available Erosion is a highly prevalent condition known as a non-carious lesion that causes progressive tooth wear due to chemical processes that do not involve the action of bacteria. Speckle images proved sensitive to even minimal mineral loss from the enamel. The aim of the present study was to investigate the use of laser speckle imaging analysis in the spatial domain to quantify shifts in the microstructure of the tooth surface in an erosion model. 32 fragments of the vestibular surface of bovine incisors were divided in for groups (10 min, 20 min. 30 min and 40 min of acid etching immersed in a cola-based beverage (pH approximately 2.5 twice a day during 7 days to create an artificial erosion. By analyzing the laser speckle contrast map (LASCA in the eroded region compared to the sound it was observed that the LASCA map shifts, proportionally to the acid each duration, by: 18%; 23%; 39% and 44% for the 10 min; 20 min; 30 min and 40 min groups, respectively. To the best of our knowledge, this is the first study to demonstrate the correlation between speckle patterns and erosion progression.

  6. Incidence and Pattern of Dental Erosion in Gastroesophageal Reflux Disease Patients.

    Science.gov (United States)

    Ramachandran, Anupama; Raja Khan, Sulthan Ibrahim; Vaitheeswaran, Nandinee

    2017-11-01

    Gastroesophageal reflux disease (GERD) is a very common condition whose consequences of are localized not only in the esophagus; extra-esophageal involvement has frequently been reported. The aim of the study is to examine the incidence and pattern of dental erosion in GERD patients. A total of 50 patients were recruited in this study (control -25 and GERD -25). All participants diagnosed having GERD by the endoscopic examination by their gastroenterologist are included. The patients were examined for dental erosion and will be quantified using Basic erosive wear examination index. The results showed that the incidence of dental erosion was 88% as compared to 32% in the control group which was found to be statistically significant.

  7. THE USE OF BIOTEXTILES TO RECUPERATE DEGRADADED AREAS BY EROSION

    OpenAIRE

    Marcia Silva Furtado; Neilianne de Fátima Costa Lima; Ulisses Denache Vieira Souza; Jane Karina Silva Mendonça; Antônio Teixeira Guerra; Antonio Cordeiro Feitosa

    2005-01-01

    The erosion is a process that results from the conjunct action of many natural agents over the grounds. However, this process can be accelerated, mainly by the action of the human being that has caused numerous degrading actions of the environment, depending on the level of intensity and from the characteristic of his intervention. Among the ways of degradation it is possible to stand out accelerated erosive processes, like ravines and gullies.These processes can be mitigated with the use of ...

  8. A comparative study of tribological behavior of plasma and D-gun sprayed coatings under different wear modes

    International Nuclear Information System (INIS)

    Sundararajan, G.; Rao, D.S.; Prasad, K.U.M.; Joshi, S.V.

    1998-01-01

    In recent years, thermal sprayed protective coatings have gained widespread acceptance for a variety of industrial applications. A vast majority of these applications involve the use of thermal sprayed coatings to combat wear. While plasma spraying is the most versatile variant of all the thermal spray processes, the detonation gun (D-gun) coatings have been a novelty until recently because of their proprietary nature. The present study is aimed at comparing the tribological behavior of coatings deposited using the two above techniques by focusing on some popular coating materials that are widely adopted for wear resistant applications, namely, WC-12% Co, Al 2 O 3 , and Cr 3 C 2 -NiCr. To enable a comprehensive comparison of the above indicated thermal spray techniques as well as coating materials, the deposited coatings were extensively characterized employing microstructural evaluation, microhardness measurements, and XRD analysis for phase constitution. The behavior of these coatings under different wear modes was also evaluated by determining their tribological performance when subjected to solid particle erosion tests, rubber wheel sand abrasion tests, and pin-on-disk sliding wear tests. Among all the coating materials studied, D-gun sprayed WC-12% Co, in general, yields the best performance under different modes of wear, whereas plasma sprayed Al 2 O 3 shows least wear resistance to every wear mode

  9. A study of microstructure and wear behaviour of TiB2/Al metal matrix composites

    Directory of Open Access Journals (Sweden)

    A. Sreenivasan

    Full Text Available The present paper deals with the study of microstructure and wear characteristics of TiB2 reinforced aluminium metal matrix composites (MMCs. Matrix alloys with 5, 10 and 15% of TiB2 were made using stir casting technique. Effect of sliding velocity on the wear behaviour and tribo-chemistry of the worn surfaces of both matrix and composites sliding against a EN24 steel disc has been investigated under dry conditions. A pin-on-disc wear testing machine was used to find the wear rate, in which EN24 steel disc was used as the counter face, loads of 10-60N in steps of 10N and speeds of 100, 200, 300, 400 and 500 rpm were employed. The results showed that the wear rate was increased with an increase in load and sliding speed for both the materials. However, a lower wear rate was obtained for MMCs when compared to the matrix alloys. The wear transition from slight to severe was presented at the critical applied loads. The transition loads for the MMCs were much higher than that of the matrix alloy. The transition loads were increased with increase in TiB2 and the same was decreased with the increase of sliding speeds. The SEM and EDS analyses were undertaken to demonstrate the effect of TiB2 particles on the wear mechanism for each conditions.

  10. A State of the Art Report on Wear Damage of Steam Generator Tubes

    International Nuclear Information System (INIS)

    Lim, Yun Soo; Kim, Joung Soo; Kim, Hong Pyo; Hwang, Seong Sik; Jung, Man Kyo

    2004-10-01

    The recent status on wear damage of steam generator tubes caused by flow-induced vibration was investigated, and the criteria for structural integrity evaluation of the wear-damaged tubes were reviewed. It was surveyed how the wear damage of tubes could be affected by main parameters, such as, materials properties and their combination, impact load and vibration amplitude/frequency, contact areas and diametral clearance between the tube and tube support plate, wear test duration, and test temperature. Finally, corrosive wear, which means the combined action of corrosion and wear simultaneously, was also surveyed in this report. There has been only a few works concerned on the wear damage of steam generator tubes in Korea, compared with the leading foreign research institutes. Especially, the experience related to the wear characteristics of Alloy 690, which has become a replacement material for Alloy 600 as steam generator tubes, is far from satisfactory. Systematic studies, therefore, concerned with structural integrity of tubes as well as improvement of were resistance of Alloy 690 in the PWR environment are needed

  11. Sliding wear studies of sprayed chromium carbide-nichrome coatings for gas-cooled reactor applications

    International Nuclear Information System (INIS)

    Li, C.C.; Lai, G.Y.

    1978-09-01

    Chromium carbide-nichrome coatings being considered for wear protection of some critical components in high-temperature gas-cooled reactors (HTGR's) were investigated. The coatings were deposited either by the detonation gun or the plasma-arc process. Sliding wear tests were conducted on specimens in a button-on-plate arrangement with sliding velocities of 7.1 x 10 -3 and 7.9 mm/s at 816 0 C in a helium environment simulates HTGR primary coolant chemistry. The coatings containing 75 or 80 wt % chromium carbide exhibited excellent wear resistance. As the chromium carbide content decreased from either 80 or 75 to 55 wt %, with a concurrent decrease in coating hardness, wear-resistance deteriorated. The friction and wear behavior of the soft coating was similar to that of the bare metal--showing severe galling and significant amounts of wear debris. The friction characteristics of the hard coating exhibited a strong velocity dependence with high friction coefficients in low sliding velocity tests ad vice versa. Both the soft coating and bare metal showed no dependence on sliding velocity. The wear behavior observed in this study is of adhesive type, and the wear damage is believed to be controlled primarily by the delamination process

  12. Wear rate quantifying in real-time using the charged particle surface activation

    Science.gov (United States)

    Alexandreanu, B.; Popa-Simil, L.; Voiculescu, D.; Racolta, P. M.

    1997-02-01

    Surface activation, commonly known as Thin Layer Activation (TLA), is currently employed in over 30 accelerator laboratories around the world for wear and/or corrosion monitoring in industrial plants [1-6]. TLA was primarily designed and developed to meet requirements of potential industrial partners, in order to transfer this technique from research to industry. The method consists of accelerated ion bombardment of a surface of interest, e.g., a machine part subjected to wear. Loss of material owing to wear, erosive corrosion or abrasion is characterized by monitoring the resultant changes in radioactivity. In principle, depending upon the case at hand, one may choose to measure either the remnant activity of the component of interest or to monitor the activity of the debris. For applications of the second type, especially when a lubricating agent is involved, dedicated installations have been constructed and adapted to an engine or a tribological testing stand in order to assure oil circulation around an externally placed detection gauge. This way, the wear particles suspended in the lubricant can be detected and the material loss rates quantified in real time. Moreover, in specific cases, such as the one presented in this paper, remnant activity measurements prove to be useful tools for complementary results. This paper provides a detailed presentation of such a case: in situ resistance-to-wear testing of two types of piston rings.

  13. A new methodology for predictive tool wear

    Science.gov (United States)

    Kim, Won-Sik

    An empirical approach to tool wear, which requires a series of machining tests for each combination of insert and work material, has been a standard practice for industries since early part of the twentieth century. With many varieties of inserts and work materials available for machining, the empirical approach is too experiment-intensive that the demand for the development of a model-based approach is increasing. With a model-based approach, the developed wear equation can be extended without additional machining experiments. The main idea is that the temperatures on the primary wear areas are increasing such that the physical properties of the tool material degrade substantially and consequently tool wear increases. Dissolution and abrasion are identified to be the main mechanisms for tool wear. Flank wear is predominantly a phenomenon of abrasion as evident by the presence of a scoring mark on the flank surface. Based on this statement, it is reasonable to expect that the flank-wear rate would increase with the content of hard inclusions. However, experimental flank wear results did not necessary correspond to the content of cementite phase present in the steels. Hence, other phenomena are believed to significantly affect wear behavior under certain conditions. When the cutting temperature in the flank interface is subjected to high enough temperatures, pearlitic structure austenizes. During the formation of a new austenitic phase, the existing carbon is dissolved into the ferrite matrix, which will reduce the abrasive action. To verify the austenitic transformation, turning tests were conducted with plain carbon steels. The machined surface areas are imaged using X-ray diffraction the Scanning Electron Microscope (SEM) and the Transmission Electron Microscope (TEM). On the other hand, crater wear occurs as a result of dissolution wear and abrasive wear. To verify the wear mechanisms of crater wear, various coating inserts as well as uncoated inserts were

  14. Erosion in extruder flow

    Science.gov (United States)

    Kaufman, Miron; Fodor, Petru S.

    A detailed analysis of the fluid flow in Tadmor's unwound channel model of the single screw extruder is performed by combining numerical and analytical methods. Using the analytical solution for the longitudinal velocity field (in the limit of zero Reynolds number) allows us to devote all the computational resources solely for a detailed numerical solution of the transversal velocity field. This high resolution 3D model of the fluid flow in a single-screw extruder allows us to identify the position and extent of Moffatt eddies that impede mixing. We further consider the erosion of particles (e.g. carbon-black agglomerates) advected by the polymeric flow. We assume a particle to be made of primary fragments bound together. In the erosion process a primary fragment breaks out of a given particle. Particles are advected by the laminar flow and they disperse because of the shear stresses imparted by the fluid. The time evolution of the numbers of particles of different sizes is described by the Bateman coupled differential equations used to model radioactivity. Using the particle size distribution we compute an entropic fragmentation index which varies from 0 for a monodisperse system to 1 for an extreme poly-disperse system.

  15. Spatial and temporal variations of wind erosion climatic erosivity in the farming-pastoral zone of Northern China

    Science.gov (United States)

    Yue, Shuping; Yang, Ruixin; Yan, Yechao; Yang, Zhengwei; Wang, Dandan

    2018-03-01

    Wind erosion climatic erosivity is an important parameter to assess the possible effects of climatic conditions on wind erosion. In this paper, the wind erosion climatic factor (C-factor), which was used to quantify the wind erosion climatic erosivity, was calculated for the period 1960-2014 based on monthly meteorological data collected from 101 stations in the farming-pastoral zone of Northern China. The Mann-Kendall (M-K) test, trend analysis, and geostatistical analysis methods were used to explore the spatial and temporal characteristics of the wind erosion climatic erosivity in this region. The result suggests that the annual C-factor, with a maximum of 76.05 in 1969 and a minimum of 26.57 in 2007, has a significant decreasing trend over the past 55 years. Strong seasonality in the C-factor was found, with the highest value in spring, which accounts for a significant proportion of the annual C-factor (41.46%). However, the coefficient of variation of the seasonal C-factor reaches a maximum in winter and a minimum in spring. The mean annual C-factor varies substantially across the region. Areas with high values of the mean annual C-factor (C ≥ 100) are located in Ulanqab and Dingxi, while areas with low values (C ≤ 10) lie in Lanzhou, Linxia, Dingxi, Xining, and Chengde. Spatial analysis on the trend of the C-factor reveals that 81% of the stations show statistically significant decreases at a 90% confidence level. An examination of the concentration ratio of the C-factor shows that the wind erosion climatic erosivity is concentrated in spring, especially in April, which makes this period particularly important for implementing soil conservation measures.

  16. Slurry Erosion Behavior of Destabilized and Deep Cryogenically Treated Cr-Mn-Cu White Cast Irons

    Directory of Open Access Journals (Sweden)

    S. Gupta

    2016-12-01

    Full Text Available The effects of destabilization treatment and destabilization followed by cryogenic treatment have been evaluated on the microstructural evolution and sand-water slurry erosion behavior of Cr-Mn-Cu white cast irons. The phase transformations after the destabilization and cryotreatment have been characterized by bulk hardness measurement, optical and scanning electron microscopy, x-ray diffraction analysis. The static corrosion rate has been measured in tap water (with pH=7 and the erosion-corrosion behavior has been studied by slurry pot tester using sand-water slurry. The test results indicate that the cryogenic treatment has a significant effect in minimizing the as-cast retained austenite content and transforming into martensitic and bainitic matrix embedded with ultra-fine M7C3 alloy carbides. In contrast, by conventional destabilization treatment retained austenite in the matrix are not fully eliminated. The slurry erosive wear resistance has been compared with reference to destabilized and cryotreated high chromium iron samples which are commonly employed for such applications. The cryotreated Cr-Mn-Cu irons have exhibited a comparable erosive wear performance to those of high chromium irons. Higher hardness combined with improved corrosion resistance result in better slurry erosion resistance.

  17. Bleaching Gels Containing Calcium and Fluoride: Effect on Enamel Erosion Susceptibility

    Directory of Open Access Journals (Sweden)

    Alessandra B. Borges

    2012-01-01

    Full Text Available This in vitro study evaluated the effect of 35% hydrogen peroxide (HP bleaching gel modified or not by the addition of calcium and fluoride on enamel susceptibility to erosion. Bovine enamel samples (3 mm in diameter were divided into four groups (n=15 according to the bleaching agent: control—without bleaching (C; 35% hydrogen peroxide (HP; 35% HP with the addition of 2% calcium gluconate (HP + Ca; 35% HP with the addition of 0.6% sodium fluoride (HP + F. The bleaching gels were applied on the enamel surface for 40 min, and the specimens were subjected to erosive challenge with Sprite Zero and remineralization with artificial saliva for 5 days. Enamel wear was assessed using profilometry. The data were analyzed by ANOVA/ Tukey’s test (P<0.05. There were significant differences among the groups (P=0.009. The most enamel wear was seen for C (3.37±0.80 μm, followed by HP (2.89 ± 0.98 μm and HP + F (2.72 ± 0.64 μm. HP + Ca (2.31 ± 0.92 μm was the only group able to significantly reduce enamel erosion compared to C. The application of HP bleaching agent did not increase the enamel susceptibility to erosion. However, the addition of calcium gluconate to the HP gel resulted in reduced susceptibility of the enamel to erosion.

  18. Dental Erosion and Dentinal Sensitivity amongst Professional Wine Tasters in South East Queensland, Australia

    Directory of Open Access Journals (Sweden)

    Roy George

    2014-01-01

    Full Text Available Background/Aims. Professional wine tasters face a hidden occupational hazard due to the high acid content in wine. This study evaluates the self-perceived dentinal sensitivity and erosive effects of wine on the professional wine tasters of the Granite Belt and the Scenic Rim regions of South East Queensland, Australia. Methods. Seventy wineries were contacted and participants were surveyed about their professional wine tasting experience and oral health. Participants were also required to rate their tooth sensitivity prior to being examined for erosion using a modified Smith & Knight tooth wear index. The data were analysed using Mann Whitney U test and Spearman’s correlation test. Results. The results showed that most participants (25 males, 22–66 yrs, brushed twice a day; however, the majority did not floss daily and had limited knowledge of the erosive effect of wine. There was a direct correlation between years of wine tasting, age of participants, and the erosion index. Correlation was not observed between the participant’s sensitivity index and erosion index. Conclusion. The lack of significant experience of dentinal hypersensitivity amongst professional wine tasters should not prevent oral health practitioners from providing necessary counselling and undertaking preventive measures, as tooth wear can have serious long-term effect on oral health of an individual.

  19. Wear behavior of AA 5083/SiC nano-particle metal matrix composite: Statistical analysis

    Science.gov (United States)

    Hussain Idrisi, Amir; Ismail Mourad, Abdel-Hamid; Thekkuden, Dinu Thomas; Christy, John Victor

    2018-03-01

    This paper reports study on statistical analysis of the wear characteristics of AA5083/SiC nanocomposite. The aluminum matrix composites with different wt % (0%, 1% and 2%) of SiC nanoparticles were fabricated by using stir casting route. The developed composites were used in the manufacturing of spur gears on which the study was conducted. A specially designed test rig was used in testing the wear performance of the gears. The wear was investigated under different conditions of applied load (10N, 20N, and 30N) and operation time (30 mins, 60 mins, 90 mins, and 120mins). The analysis carried out at room temperature under constant speed of 1450 rpm. The wear parameters were optimized by using Taguchi’s method. During this statistical approach, L27 Orthogonal array was selected for the analysis of output. Furthermore, analysis of variance (ANOVA) was used to investigate the influence of applied load, operation time and SiC wt. % on wear behaviour. The wear resistance was analyzed by selecting “smaller is better” characteristics as the objective of the model. From this research, it is observed that experiment time and SiC wt % have the most significant effect on the wear performance followed by the applied load.

  20. Coastal erosion and accretion rates in Greece

    Science.gov (United States)

    Foteinis, Spyros; Papadopoulos, Costas; Koutsogiannaki, Irini; Synolakis, Costas

    2010-05-01

    Erosion threatens many coastal regions of Greece. Anthropogenic changes of landforms such as coastal roads built on even narrow beaches, sand mining for construction, poor design of coastal structures that interfere with sediment, and dams without sediment bypasses have significantly reduced beach widths. We present erosion rates for different beaches, some of which are in sensitive ecosystems, otherwise "protected" by local and EU ordinances. By comparing inferences of beach widths in varying intervals from 1933 to 2006, we infer that the construction of dams in Acheloos river in western Greece, built in a faraonic attempt to partially divert its flows to eastern Greece, this is responsible for up to 20m/year erosion rates observed in certain locales in the Acheloos delta. More characteristic erosion rates in the region are ~ 2m/year. By contrast, there appears rapid accretion of up to 4m/year in the beaches around the Nestos delta in northern Greece (Papadopoulos, 2009). In beaches that are not near large river deltas, erosion rates range from 0.5m/year to 1m/year. While we have not done comprehensive comparisons among coastlines with different levels of coastal development, it does appear that rapid coastal development correlates well with erosion rates. The underlying problem is the complete lack of any semblance of coastal zone management in Greece and substandard design of coastal structures, which are often sited without any measurements of waves and currents offshore (Synolakis et al, 2008). Beach maintenance remains an exotic concept for most local authorities, who invariably prefer to build hard coastal structures to "protect" versus nourish, siting lack of experience with nourishment and "environmental" concerns. In certain cases, choices are dictated by costs, the larger the cost the easier the project gets approved by regulatory authorities, hence the preference for concrete or rubble structures. We conclude that, unless urgent salvage measures are

  1. Radiation tagging measures wear at speed

    International Nuclear Information System (INIS)

    Barrett, Jon.

    1994-01-01

    A new non-invasive technique for performing accelerated wear and corrosion analysis is particularly relevant to power transmission systems. Wear tests that would normally take days or weeks to complete can now be performed in hours. A tiny patch of the wearing component is made mildly radioactive and the drop in activity as material is worn away is monitored. Known as Thin Layer Activation (TLA), the technology was originally developed and pioneered in-house by the Atomic Energy Authority. Since then, the dominant partner has been the automotive sector where TLA has been used extensively for engine wear and lubrication performance analysis. However, TLA could be used in any wear or corrosion environment. Applications include wear analysis of machine tool cutting surfaces, pump impellers and brake linings to the corrosion monitoring of process plant and pipelines. (author)

  2. Effect of dental erosion on oral health among employees of battery-manufacturing units in Baddi, Himachal Pradesh, India.

    Science.gov (United States)

    Bansal, Mohit; Singh, Sunint; Bector, Aditi; Dogra, Mrigank

    2018-01-01

    The objective of the study was to obtain data on prevalence and severity of dental erosion among acid industry workers in Baddi (Himachal Pradesh). A cross-sectional study was conducted among 800 battery industry workers. The demographic details were recorded on a prestructured pro forma. Type III examination was done. Dental erosion was recorded based on the index given by Bardsley (simplified scoring criteria for tooth wear index). Appropriate statistical tests were used to interpret the data. The prevalence of dental erosion was found to be 48.6%. Prevalence increased with the duration of employment. Dental erosion was most commonly found in the labial surfaces of maxillary anterior teeth. Erosion is a condition which is multifactorial and becomes more aggravating in the presence of acidic environment. Therefore, the workers working in such conditions should be more careful, and mandatory policies should also be followed by such industries to maintain the overall health of the workers.

  3. Rill erosion rates in burned forests

    Science.gov (United States)

    Joseph W. Wagenbrenner; Peter R. Robichaud

    2011-01-01

    Introduction Wildfires often produce large increases in runoff and erosion rates (e.g., Moody and Martin, 2009), and land managers need to predict the frequency and magnitude of postfire erosion to determine the needs for hazard response and possible erosion mitigation to reduce the impacts of increased erosion on public safety and valued resources. The Water Erosion...

  4. Investigation of counterface surface topography effects on the wear and transfer behaviour of a POM-20% PTFE composite

    NARCIS (Netherlands)

    Franklin, S.E.; de Kraker, A.

    2003-01-01

    In order to gain greater insight into the relation between the wear rate, counterface surface topography and the characteristics of the transfer layer formed, a series of wear experiments have been performed with a commercial POM-20% PTFE composite sliding against hardened tool steel counterfaces in

  5. Abrasive wear mechanisms and surface layer structure of refractory materials after mechanical working

    International Nuclear Information System (INIS)

    Milman, Y.V.; Lotsko, D.V.

    1989-01-01

    The mechanisms of abrasive wear and surface layer structure formation after different kinds of mechanical working are considered in terms of fracture and plastic deformation mechanisms for various refractory materials. The principles for classification of abrasive wear mechanisms are proposed, the four types of wear mechanisms are distinguished for various combinations of fractures and plastic deformation types. The concept of characteristic deformation temperature t * (knee temperature) is used. Detailed examples are given of investigating the surface layer structures in grinded crystals of sapphire and molybdenum. The amorphisation tendency of the thinnest surface layer while mechanical polishing is discussed separately. 19 refs., 11 figs., 2 tabs. (Author)

  6. Recent developments in wear measurements with the thin layer activation technique. Neuere Entwicklungen der Verschleissmesstechnik mit dem Verfahren der Duennschichtaktivierung

    Energy Technology Data Exchange (ETDEWEB)

    Kleinrahm, A.; Fehsenfeld, P. (Kernforschungszentrum Karlsruhe GmbH (Germany, F.R.). Inst. fuer Kernphysik 3)

    1989-01-01

    At the KfK's compact cyclotron an efficient serial radiation plant for the thin-layer activation of machine and plant components for industry and research was provided. By means of this fully automatic plant it is possible to carry out wear measurements on ceramic compositions, cermets and related hard materials. The further developed RTM activation and measuring technique was used for the investigation of the erosive and corrosive wear behaviour of pipelines and pump parts in liquid mediums with solid matter proportions, in the field of textile technology (knitting machines) and for the detection of material dislocations in the bearing surface of wheel-rail-tribo-systems. (DG).

  7. An index guiding temporal planting policies for wind erosion reduction

    NARCIS (Netherlands)

    Zhao, C.X.; Zheng, D.W.; Stigter, C.J.; He, W.Q.; Tuo, D.B.; Zhao, P.

    2006-01-01

    Vegetation cover has spatial as well as temporal characteristics, but the latter are often neglected. Temporal cover characteristics were explored to recommend planting policies for returning arable land into land better protected from serious wind erosion during late autumn, winter, and

  8. Severe tooth wear in Prader-Willi syndrome. A case–control study

    Directory of Open Access Journals (Sweden)

    Saeves Ronnaug

    2012-05-01

    Full Text Available Abstract Background Prader-Willi syndrome (PWS is a rare complex multsystemic genetic disorder characterized by severe neonatal hypotonia, endocrine disturbances, hyperphagia and obesity, mild mental retardation, learning disabilities, facial dysmorphology and oral abnormalities. The purpose of the present study was to explore the prevalence of tooth wear and possible risk factors in individuals with Prader-Willi syndrome. Methods Forty-nine individuals (6-40 years with PWS and an age- and sex-matched control group were included. Tooth wear was evaluated from dental casts and intraoral photographs and rated by four examiners using the Visual Erosion Dental Examination (VEDE scoring system and the individual tooth wear index IA. In accordance with the VEDE scoring system, tooth wear was also evaluated clinically. Whole saliva was collected. Results Mean VEDE score was 1.70 ± 1.44 in the PWS group and 0.46 ± 0.36 in the control group (p A was 7.50 (2.60-30.70 in the PWS group and 2.60 (0.90-4.70 among controls (p A; r = 0.82, p A; r = 0.43, p = 0.002. Tooth grinding was also associated with tooth wear in the PWS group, as indicated by the mean VEDE 2.67 ± 1.62 in grinders and 1.14 ± 0.97 in non-grinders (p = 0.001 and median IA values 25.70 (5.48-68.55 in grinders and 5.70 (1.60-9.10 in non-grinders (p = 0.003. Multivariate linear regression analysis was performed with tooth wear as the dependent variable and PWS (yes/no, age, tooth grinding and saliva secretion as independent variables. PWS (yes/no, age and tooth grinding retained a significant association with tooth wear, VEDE (p A (p  Conclusions Our study provides evidence that tooth wear, in terms of both erosion and attrition, is a severe problem in Prader-Willi syndrome. There is therefore considerable need for prosthodontic rehabilitation in young adults with PWS.

  9. Prevalence and risk factors of dental erosion in American children.

    Science.gov (United States)

    Habib, Mariam; Hottel, Timothy L; Hong, Liang

    2013-01-01

    The purpose of this study was to assess the prevalence and characteristics of dental erosion in children aged 2-4 years old and 12 years old. 243 subjects were recruited from daycare centers, preschools, and grade schools; they received dental examinations assessing their condition of dental erosion, including both depth and area of tooth surface loss on four maxillary incisors. Questionnaires were given to the subjects to obtain socio-demographic, oral health behaviors at home, and access to dental care. Dental erosion was analyzed and risk factors were assessed using Chi-Square and logistic regression analysis. The subjects were 60% Caucasians, 31% Black, 7% Hispanic and others were 2%. 34% of children could not get the dental care they needed within the past 12 months and 61% of all children brushed their teeth twice or more daily. Overall, 12% of study children had dental erosion with 13% for 2-4 years old and 10% for 12 years old, with the majority of erosive lesions within enamel. Family income (OR 3.98, p = 0.021) and acidic fruit juice consumption (OR 2.38, p = 0.038) were significant risk factors for dental erosion, even after controlling for other factors, such as source of drinking water and oral hygiene using logistic regression analysis. Dental erosion is a relatively common problem among the children in this study and it is seen as a multi-factorial process.

  10. Fenomen erozije cevi naoružanja / Gun barrel erosion

    Directory of Open Access Journals (Sweden)

    Slobodan Ilić

    2009-07-01

    Full Text Available U radu su prikazana dosadašnja istraživanja erozije cevi. Trošenje cevi je neizbežan proces do kojeg dolazi pri svakom opaljenju. Erozija cevi može se definisati kao progresivna povreda ili oštećenje površine cevi i proširenje kalibra usled opaljenja, koja utiče na: gubitak ili pad početne brzine projektila, tačnost i efektivnost oruđa. Kao glavni uzročnici koji utiču na intenzitet erozije cevi opisani su termički, hemijski i mehanički faktori. Njihov uticaj prikazan je u interakciji cev-projektil-barutno punjenje. / An overview of research into gun barrel erosion is presented in this paper. The gun bore wear is an unavoidable process during normal firing. The wear can be defined as progressive damage of the bore surface and enlargement of the bore, ultimately resulting in loss in the muzzle velocity, range and accuracy. Thermal, chemical and mechanical factors are described as major factors of gun barrel erosion. The influence of these factors is presented in the interaction of gun tube - projectile - propellant.

  11. Standard test method for ranking resistance of materials to sliding wear using block-on-ring wear test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This test method covers laboratory procedures for determining the resistance of materials to sliding wear. The test utilizes a block-on-ring friction and wear testing machine to rank pairs of materials according to their sliding wear characteristics under various conditions. 1.2 An important attribute of this test is that it is very flexible. Any material that can be fabricated into, or applied to, blocks and rings can be tested. Thus, the potential materials combinations are endless. However, the interlaboratory testing has been limited to metals. In addition, the test can be run with various lubricants, liquids, or gaseous atmospheres, as desired, to simulate service conditions. Rotational speed and load can also be varied to better correspond to service requirements. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. Wear test results are reported as the volume loss in cubic millimetres for both the block and ring. Materials...

  12. The role of hardness and microstructure in high temperature pitting in the impact wear of 9Cr boiler material. Part 1

    International Nuclear Information System (INIS)

    Morri, J.

    1987-11-01

    This report describes impact wear experiments on 9Cr1Mo finned boiler tube specimens in 3 different heat treated forms. The objective of the tests was to establish whether a high temperature, high wear rate, pitting form of wear was dependent upon the residual microstructure and hardness. Although a x2 reduction in specific wear rate was achieved for the martensitic structure, the pitting characteristic remained. It is concluded that modifying the as-received 9Cr microstructure has not suppressed the high temperature severe form of wear. (author)

  13. Determination of rail wear and short-time wear measurements of rails applying radioisotopes

    International Nuclear Information System (INIS)

    Grohmann, H.D.

    1981-01-01

    An energetic model has been developed for calculating rail wear. Short-time wear tests on rails after surface activation and following activity measurements showed a good agreement with the calculated values

  14. Friction & Wear Under Very High Electromagnetic Stress

    National Research Council Canada - National Science Library

    Cowan, Richard S; Danyluk, Steven; Moon, Francis; Ford, J. C; Brenner, Donald W

    2004-01-01

    This document summarizes initial progress toward advancing the fundamental understanding of the friction, wear and mechanics of interfaces subjected to extreme electromagnetic stress, high relative...

  15. Daily Water Requirements when Wearing Body Armor

    National Research Council Canada - National Science Library

    Montain, Scott

    2000-01-01

    .... This report presents the results of model simulations predicting the individual daily water requirements under a broad range of energy expenditures and weather conditions when wearing battle dress...

  16. Polarization sensitive camera for the in vitro diagnostic and monitoring of dental erosion

    Science.gov (United States)

    Bossen, Anke; Rakhmatullina, Ekaterina; Lussi, Adrian; Meier, Christoph

    Due to a frequent consumption of acidic food and beverages, the prevalence of dental erosion increases worldwide. In an initial erosion stage, the hard dental tissue is softened due to acidic demineralization. As erosion progresses, a gradual tissue wear occurs resulting in thinning of the enamel. Complete loss of the enamel tissue can be observed in severe clinical cases. Therefore, it is essential to provide a diagnosis tool for an accurate detection and monitoring of dental erosion already at early stages. In this manuscript, we present the development of a polarization sensitive imaging camera for the visualization and quantification of dental erosion. The system consists of two CMOS cameras mounted on two sides of a polarizing beamsplitter. A horizontal linearly polarized light source is positioned orthogonal to the camera to ensure an incidence illumination and detection angles of 45°. The specular reflected light from the enamel surface is collected with an objective lens mounted on the beam splitter and divided into horizontal (H) and vertical (V) components on each associate camera. Images of non-eroded and eroded enamel surfaces at different erosion degrees were recorded and assessed with diagnostic software. The software was designed to generate and display two types of images: distribution of the reflection intensity (V) and a polarization ratio (H-V)/(H+V) throughout the analyzed tissue area. The measurements and visualization of these two optical parameters, i.e. specular reflection intensity and the polarization ratio, allowed detection and quantification of enamel erosion at early stages in vitro.

  17. The erosive potential of lollipops

    NARCIS (Netherlands)

    Brand, H.S.; Gambon, D.L.; Paap, A.; Bulthuis, M.S.; Veerman, E.C.I.; Nieuw Amerongen, A.V.

    2009-01-01

    Aim: To determine the erosive potential of several commercially available lollipops and the protective effect of saliva. Methods: The erosive potential of lollipops was determined in vitro by measuring the pH and neutralisable acidity. Subsequently, 10 healthy volunteers tested different types of

  18. Wind erosion processes and control

    Science.gov (United States)

    Wind erosion continues to threaten the sustainability of our nations' soil, air, and water resources. To effectively apply conservation systems to prevent wind driven soil loss, an understanding of the fundamental processes of wind erosion is necessary so that land managers can better recognize the ...

  19. The effects of various reinforcements on dry sliding wear behaviour of AA 6061 nanocomposites

    International Nuclear Information System (INIS)

    Jeyasimman, D.; Narayanasamy, R.; Ponalagusamy, R.; Anandakrishnan, V.; Kamaraj, M.

    2014-01-01

    Highlights: • Wear and friction coefficient of nanocomposites were investigated. • The worn surface morphologies of nanocomposites were analysed. • The wear rate was increased with increasing load and sliding velocity. • The friction coefficient was decreased with increasing load and sliding velocity. - Abstract: The present work aims to investigate the dry sliding wear behaviour of AA 6061 nanocomposites reinforced with various nanolevel reinforcements, such as titanium carbide (TiC), gamma phase alumina (γ-Al 2 O 3 ) and hybrid (TiC + Al 2 O 3 ) nanoparticles with two weight percentages (wt.%) prepared by 30 h of mechanical alloying (MA). The tests were performed using a pin-on-disk wear tester by sliding these pin specimens at sliding speeds of 0.6, 0.9 and 1.2 m/s against an oil-hardened non-shrinking (OHNS) steel disk at room temperature. Wear tests were conducted for normal loads of 5, 7 and 10 N at different sliding speeds at room temperature. The variations of the friction coefficient and the wear rate with the sliding distances (500 m, 1000 m and 1600 m) for different normal loads and sliding velocities were plotted and investigated. To observe the wear characteristics and to investigate the wear mechanism, the morphologies of the worn surfaces were analysed using a scanning electron microscope (SEM). The formation of an oxide layer on the worn surface was examined by energy dispersive spectroscopy (EDS). The wear rate was found to increase with the load and sliding velocity for all prepared nanocomposites. Hybrid (TiC + Al 2 O 3 ) reinforced AA 6061 nanocomposites had lower wear rates and friction coefficients compared with TiC and Al 2 O 3 reinforced AA 6061 nanocomposites

  20. Erosion--corrosion

    International Nuclear Information System (INIS)

    Vyas, B.

    1978-01-01

    The deterioration of materials by corrosion or erosion by itself presents a formidable problem and for this reason investigators have studied these two phenomena independently. In fact, there are very few systematic studies on E-C and the majority of references mention it only in passing. In most real systems, however, the two destructive processes take place simultaneously, hence the purpose of this review is to present the various interactions between the chemical and mechanical agents leading to accelerated degradation of the material. The papers cited in the review are those that lead to a better understanding of the process involved in the accelerated rate of material loss under E-C conditions

  1. Friction and wear behavior of Colmonoy and Stellite alloys in sodium environment

    International Nuclear Information System (INIS)

    Kanoh, S.; Mizobuchi, S.; Atsumo, H.

    1976-01-01

    A description is given of a series of experiments in sodium environment for the research and development of friction and wear resistant material used for the sliding components of sodium cooled fast breeder reactor. The study relates to the friction and wear characteristics of nickel-base alloy, Colmonoy, and cobalt-base alloy, Stellite, with respect to temperature, load, sliding velocity, sliding mode, and sodium flushing. The friction behavior of these alloys in sodium is compared with that in argon

  2. In-Situ Measurement of Hall Thruster Erosion Using a Fiber Optic Regression Probe

    Science.gov (United States)

    Polzin, Kurt; Korman, Valentin

    2009-01-01

    One potential life-limiting mechanism in a Hall thruster is the erosion of the ceramic material comprising the discharge channel. This is especially true for missions that require long thrusting periods and can be problematic for lifetime qualification, especially when attempting to qualify a thruster by analysis rather than a test lasting the full duration of the mission. In addition to lifetime, several analytical and numerical models include electrode erosion as a mechanism contributing to enhanced transport properties. However, there is still a great deal of dispute over the importance of erosion to transport in Hall thrusters. The capability to perform an in-situ measurement of discharge channel erosion is useful in addressing both the lifetime and transport concerns. An in-situ measurement would allow for real-time data regarding the erosion rates at different operating points, providing a quick method for empirically anchoring any analysis geared towards lifetime qualification. Erosion rate data over a thruster s operating envelope would also be useful in the modeling of the detailed physics inside the discharge chamber. There are many different sensors and techniques that have been employed to quantify discharge channel erosion in Hall thrusters. Snapshots of the wear pattern can be obtained at regular shutdown intervals using laser profilometry. Many non-intrusive techniques of varying complexity and sensitivity have been employed to detect the time-varying presence of erosion products in the thruster plume. These include the use quartz crystal microbalances, emission spectroscopy, laser induced flourescence, and cavity ring-down spectroscopy. While these techniques can provide a very accurate picture of the level of eroded material in the thruster plume, it is more difficult to use them to determine the location from which the material was eroded. Furthermore, none of the methods cited provide a true in-situ measure of erosion at the channel surface while

  3. Relationship between dental erosion and respiratory symptoms in patients with gastro-oesophageal reflux disease.

    Science.gov (United States)

    Wang, Geng-Ru; Zhang, Hui; Wang, Zhong-Gao; Jiang, Guang-Shui; Guo, Cheng-Hao

    2010-11-01

    Both dental erosion and respiratory symptoms are extra-oesophageal manifestations of gastro-oesophageal reflux disease (GERD). The aim of this study was to determine whether dental erosion was correlated with respiratory symptoms in GERD patients. 88 GERD patients were recruited and assigned to three groups mainly according to the frequency of respiratory symptoms: Group I: never; Group II: occasional (1-2 days a week or less); Group III: frequent (3-5 days a week or more). All patients underwent medical evaluations, including medical history, questionnaire answering and alimentary tract examinations. Dental examinations were carried out on these patients and 36 healthy controls. Dental erosions were measured by modified method of Smith and Knight Tooth Wear Index (TWI). Location and severity of dental erosion were recorded. The prevalence of dental erosion in Group III (64.52%) was higher (pdental erosion with TWI scores ranging from 1 to 4. Though proportion of dental erosion with Score 2 (7/20) in Group III was higher than that in Group I (2/11) and Group II (3/12), there was no statistical significance in the proportions of erosion scores among three patient groups. Correlation coefficient between airway symptoms and scores of dental erosion was 0.231 (perosion of upper incisor was seen in 8 persons (72.7%) in Group I, 9 persons (75%) in Group II and 16 persons (80%) in Group III (p>0.05). Labial erosion of upper incisors was found in 1 person in Groups I and II respectively and 4 persons in Group III. All patients with labial erosion on upper incisors had palatal erosion, except 1 patient in Group III. In GERD patients, dental erosions are more prevalent in patients with frequent respiratory symptoms than those in patients with occasional and without respiratory symptoms. Palatal erosion of upper incisor is the main manifestation in patients. Acid reflux is the main causative factor of dental erosion in GERD patients with airway symptoms. Copyright © 2010

  4. Radiologic comparison of erosive polyarthritis with prominent interphalangeal involvement

    International Nuclear Information System (INIS)

    Gold, R.H.; Bassett, L.W.; Theros, E.G.

    1982-01-01

    Psoriatic arthritis, Reiter's disease, and multicentric reticulohistiocytosis may manifest prominent interphalangeal joint and cutaneous involvement. All three disorders may also affect the sacroiliac joints and spine. Despite these similarities, there are basic radiologic differences enabling distinction between the three disorders. Erosive osteoarthritis must also be considered in the differential diagnosis of interphalangeal erosive arthritis. Psoriatic erosions are characteristically ill defined, often bilaterally asymmetrical, usually unaccompanied by significant osteoporosis, and frequently associated with florid proliferation of subperiosteal new bone. An unilateral polyarticular pattern, which often occurs in a single ray, is the most prevalent of several patterns of involvement. Reiter's disease exhibits many clinical and radiologic similarities to psoriatic arthritis, but in the former there tends to be selective involvement of the joints of the lower limbs and particularly the feet, with relative sparing of the hands and wrists, while in the latter the joints of the upper and lower limbs tend to be involved to an equal extent. Multicentric reticulohistiocytosis (MR). Lesions predominate in skin and synovium and result in sharply circumscribed, rapidly progressive, strikingly bilaterally symmetrical erosions spreading from joint margins to articular surfaces. Most or all of the diarthrodial joints may be affected, but interphalangeal joint predominance and early and severe atlanto-axial involvement are characteristic. Erosive osteoarthritis is characterized by interphalangeal subchondral erosions, accompanying periosteal new bone that is more subtle than that of psoriatic arthritis, and interphalangeal bony ankylosis that occurs with the same frequency as that of psoriatic arthritis. (orig.)

  5. The influence of frequently consumed beverages and snacks on dental erosion among preschool children in Saudi Arabia.

    Science.gov (United States)

    Al-Dlaigan, Yousef H; Al-Meedania, Laila A; Anil, Sukumaran

    2017-12-11

    To determine the prevalence of dental erosion and its association to commonly used beverages and snacks among 3 to 5 year old preschool children in Riyadh, Saudi Arabia. Three hundred eighty-eight preschool children between 3 and 5 years old were selected from 10 different schools using a cluster random sample selection; there were 184 (47%) boys and 204 (53%) girls. The surfaces of each tooth were examined for erosion, and the level of tooth wear was recorded. Data on the frequently used beverages and snacks were obtained by questionnaires completed by the parents of the preschool children. Among the 388 children examined, 47% exhibited low erosion, 10% exhibited moderate erosion and 4% exhibited severe erosion. There was no statistically significant difference between boys and girls in terms of the prevalence of erosion. Sixty percent of the children regularly consumed juice drinks. Among daily consumers, 84% of children showed erosion prevalence with strongly significant association (p erosion (p dental erosion and the frequency of citrus and carbonated juice consumed by the preschool children in Saudi Arabia.

  6. Laser processing of cast iron for enhanced erosion resistance

    International Nuclear Information System (INIS)

    Chen, C.H.; Altstetter, C.J.; Rigsbee, J.M.

    1984-01-01

    The surfaces of nodular and gray cast iron have been modified by CO 2 laser processing for enhanced hardness and erosion resistance. Control of the near-surface microstructure was achieved primarily by controlling resolidification of the laser melted layer through variations in laser beam/target interaction time and beam power density. Typical interaction times and power densities used were 5 msec and 500 kW/cm 2 . Two basic kinds of microstructure can be produced-a feathery microstructure with high hardness (up to 1245 HV) and a dendritic microstructure with a metastable, fully austenitic matrix and lower hardness (600 to 800 HV). Erosion testing was done using slurries of SiO 2 or SiC in water. Weight loss and crater profile measurements were used to evaluate the erosion characteristics of the various microstructures. Both ductile and gray cast iron showed marked improvement in erosion resistance after laser processing

  7. Active Anti-erosion Protection Strategy in Tamarisk (Tamarix aphylla)

    Science.gov (United States)

    Han, Zhiwu; Yin, Wei; Zhang, Junqiu; Niu, Shichao; Ren, Luquan

    2013-12-01

    Plants have numerous active protection strategies for adapting to complex and severe environments. These strategies provide endless inspiration for extending the service life of materials and machines. Tamarisk (Tamarix aphylla), a tree that thrives in raging sandstorm regions, has adapted to blustery conditions by evolving extremely effective and robust erosion resistant characteristics. However, the relationships among its surface cracks, internal histology and biomechanics, such as cracks, rings, cells, elasticity modulus and growth stress, which account for its erosion resistance, remain unclear. This present study reveals that the directionally eccentric growth rings of tamarisk, which are attributed to reduced stress and accelerated cell division, promote the formation of surface cracks. The windward rings are more extensive than the leeward side rings. The windward surfaces are more prone to cracks, which improves erosion resistance. Our data provide insight into the active protection strategy of the tamarisk against wind-sand erosion.

  8. Estimating soil erosion losses in Korea with fallout cesium-137

    International Nuclear Information System (INIS)

    Menzel, R.G.; Pilkyun Jung; Kwanshig Ryu; Kitai Um

    1987-01-01

    The contents of fallout 137 Cs in soil profiles were used to estimate erosion losses from steeply sloping croplands in Korea. Seven undisturbed sites with no apparent erosion or deposition, and 15 cropland sites were examined to a depth of 30 cm. The cropland sites had been cultivated for periods ranging from 5 to more than 80 y (median 10 y), and their slopes ranged from 5 to 26% (median 13%). All except one of the cropland sites contained less 137 Cs than undisturbed sites in the same area. Three cropland sites contained essentially no 137 Cs, indicating erosion of the entire cultivated layer of soil in from 6 to 10 years. Other cropland sites, particularly those with sandy texture, showed little loss of 137 Cs over longer periods of cultivation. Cesium-137 measurements may be useful in identifying site characteristics that reduce the vulnerability of sloping soils to erosion damage. (author)

  9. Influence of Surfactants and Fluoride against Enamel Erosion.

    Science.gov (United States)

    Zanatta, Rayssa Ferreira; Ávila, Daniele Mara da Silva; Miyamoto, Karen Mayumi; Torres, Carlos Rocha Gomes; Borges, Alessandra Bühler

    2018-06-06

    This study investigated the effect of surfactants associated with sodium fluoride (NaF) on enamel erosion prevention, using an erosion-remineralization in vitro model. Sodium lauryl sulfate (SLS), polysorbate 20 (P20), and cocoamidopropyl betaine (CAPB) were tested, at concentrations of 1.0 and 1.5%, and associated or not with NaF (275 ppm). The control groups were distilled water and the NaF solution. Bovine enamel samples (n = 12) were prepared and submitted to a 5-day cycling model: acid challenge (0.3% citric acid, pH 2.6, 4×/day), human saliva (2 h, 4×/day), and the treatment solutions (2 min, 2×/day). The protective potential of the agents against initial erosion was assessed by microhardness and the surface loss by profilometry. Enamel surface wettability was determined by goniometry, protein adsorption was measured by spectroscopy (FTIR), and the KOH-soluble fluoride was quantified. Goniometry showed that SLS and CAPB increased enamel wettability. No differences were found among the surfactants regarding protein adsorption. Microhardness showed that SLS reduced NaF protection. P20 (1 and 1.5%) and CAPB 1.5% presented a protective effect, but lower than the NaF solution. Profilometry showed that CAPB protected enamel, but no agent associated with NaF promoted a higher protection than the NaF solution alone. KOH-soluble fluoride analysis showed that all surfactants reduced the fluoride adsorption on the enamel surface. Therefore, the surfactants tested (except for P20) changed the enamel surface energy. The SLS decreased the protective potential of NaF on initial erosion, but no tested agent interfered with the protective effect of NaF on enamel erosive wear. © 2018 S. Karger AG, Basel.

  10. Using REE tracers to measure sheet erosion changing to rill erosion

    International Nuclear Information System (INIS)

    Liu Puling; Xue Yazhou; Song Wei; Wang Mingyi; Ju Tongjun

    2004-01-01

    Rare Earth Elements (REE) tracer method was used to study sheet erosion changing to rill erosion on slope land. By placing different rare earth elements of different soil depth across a slope in an indoor plot, two simulated rainfalls were applied to study the change of erosion type and the rill erosion process. The results indicate that the main erosion type is sheet erosion at the beginning of the rainfalls, and serious erosion happens after rill erosion appears. Accumulated sheet and rill erosion amounts increase with the rainfalls time. The percentage of sheet erosion amount decreases and rill erosion percentage increases with time. At the end of the rainfalls, the total rill erosion amounts are 4-5 times more than sheet erosion. In this paper, a new REE tracer method was used to quantitatively distinguish sheet and rill erosion amounts. The new REE tracer method should be useful to future studying of erosion processes on slope lands. (authors)

  11. Shoreline Erosion and Proposed Control at Experimental Facility 15-Spesutie Island

    Science.gov (United States)

    2017-09-01

    distribution is unlimited. 1 1. Introduction Coastal erosion is the wearing away of land and the removal of beach or dune sediments by wave action...the land , air, and water defines the wetted perimeter where land use and clearing practices have taken on an adversarial role with regard to the...stand with approximately 30–40 ft of manicured lawn to the shoreline. There are no trees on the range proper, with only a smattering of indigenous

  12. Surface and sliding wear behaviour of different coatings and steels

    Energy Technology Data Exchange (ETDEWEB)

    Vera-Cardenas, E.E. [Universidad Politecnica de Pachuca, Zempoala, Hidalgo (Mexico)]. E-mail: evera@upp.edu.mx; Vite-Torres, M. [Instituto Politecnico Nacional, Mexico D.F. (Mexico)]. E-mail: drmanulvite9@hotmail.com; Lewis, R. [University of Sheffield (United Kingdom)]. E-mail: roger.lewis@sheffield.ac.uk

    2012-01-15

    In this work, the sliding wear behaviour of the coatings TiN, CrN and WC/C applied on steel substrates was studied using a reciprocating wear test machine. All tests were carried out in dry conditions, at room temperature (20-23 degrees Celsius and 45% - 50% relative humidity). The average sliding velocity was 0.08 m/s and an amplitude of 2 mm was used. The applied loads were 11.76 N (Po = 1.74 GPa) and 7.84 N (Po = 1.52 GPa). Optical microscopy was used to observe the characteristics of wear scars and spalls and possible causes of their formation. The variation of the friction coefficient against the number of cycles was obtained. This was used to determine more precisely the time (number of cycles) where the coating presented the first signs of wear, in addition Energy Dispersive X-ray analysis (EDS) was performed, as well as Scanning Electron Microscopy (SEM) and hardness tests on the wear traces, which reinforced the previous observations. Thus it was possible to know the wear life of different coatings and possible causes of variation. Increasing the load was an important factor in the variation of wear life results. But it is also important to consider other factors such as surface roughness and thickness of coatings. [Spanish] En este trabajo se estudio el comportamiento en desgaste por deslizamiento de los recubrimientos de TiN, CrN y WC/C aplicados sobre sustratos de acero. Las pruebas se realizaron con una maquina reciprocante en condiciones secas a temperatura ambiente (20-23 grados centigrados y 45% - 50% de humedad relativa). Se empleo una velocidad promedio de 0.08 m/s y una amplitud de 2 mm. Las cargas aplicadas fueron de 11.76N (Po = 1.74 GPa) y de 7.84 N (Po = 1.52 GPa). Se realizo microscopia optica para observar las caracteristicas de las zonas de desgaste y sus posibles causas de formacion. Se obtuvo graficamente la variacion del coeficiente de friccion con el numero de ciclos. Estos datos se emplearon para determinar con mayor precision el

  13. Modeling soil erosion in a watershed

    OpenAIRE

    Lanuza, R.

    1999-01-01

    Most erosion models have been developed based on a plot scale and have limited application to a watershed due to the differences in aerial scale. In order to address this limitation, a GIS-assisted methodology for modeling soil erosion was developed using PCRaster to predict the rate of soil erosion at watershed level; identify the location of erosion prone areas; and analyze the impact of landuse changes on soil erosion. The general methodology of desktop modeling or soil erosion at watershe...

  14. Prediction of wear rates in comminution equipment

    DEFF Research Database (Denmark)

    Jensen, Lucas Roald Dörig; Fundal, Erling; Møller, Per

    2010-01-01

    -resistant high chromium white cast iron (21988/JN/HBW555XCr21), a heat-treated wear resistant steel (Hardox 400) and a plain carbon construction steel (S235). Quartz, which accounts for the largest wear loss in the cement industry, was chosen as abrasive. Other process parameters such as velocity (1–7 m...

  15. Straylight Measurements in Contact Lens Wear

    NARCIS (Netherlands)

    van der Meulen, Ivanka J. E.; Engelbrecht, Leonore A.; van Vliet, Johannes M. J.; Lapid-Gortzak, Ruth; Nieuwendaal, Carla P.; Mourits, Maarten P.; Schlingemann, Reinier O.; van den Berg, Thomas J. T. P.

    2010-01-01

    Purpose: (1) To quantify the effect of contact lens wear on straylight in rigid and soft contact lens wearers and (2) to relate findings to morphological changes and subjective complaints. Methods: Straylight was measured using the Oculus C-Quant during contact lens wear and after contact lens

  16. Tooth Wear Inclination in Great Ape Molars.

    Science.gov (United States)

    Knight-Sadler, Jordan; Fiorenza, Luca

    2017-01-01

    Primate dietary diversity is reflected in their dental morphology, with differences in size and shape of teeth. In particular, the tooth wear angle can provide insight into a species' ability to break down certain foods. To examine dietary and masticatory information, digitized polygon models of dental casts provide a basis for quantitative analysis of wear associated with tooth attrition. In this study, we analyze and compare the wear patterns of Pongo pygmaeus, Gorilla gorillagorilla and Pan troglodytes schweinfurthii lower molars, focusing on the degree of inclination of specific wear facets. The variation in wear angles appears to be indicative of jaw movements and the specific stresses imposed on food during mastication, reflecting thus the ecology of these species. Orangutans exhibit flatter wear angles, more typical of a diet consisting of hard and brittle foods, while gorillas show a wear pattern with a high degree of inclination, reflecting thus their more leafy diet. Chimpanzees, on the other hand, show intermediate inclinations, a pattern that could be related to their highly variable diet. This method is demonstrated to be a powerful tool for better understanding the relationship between food, mastication and tooth wear processes in living primates, and can be potentially used to reconstruct the diet of fossil species. © 2017 S. Karger AG, Basel.

  17. Numerical prediction of car tire wear

    NARCIS (Netherlands)

    Lupker, H.A.; Cheli, F.; Braghin, F.; Gelosa, E.; Keckman, A.

    2004-01-01

    Due to their many economic and ecological implications, the possibility to predict tire wear is of major importance to tire manufacturers, fleet owners and governments. Based on these observations, in 2000, a three-year project named TROWS (Tire and Road Wear and Slip assessment was started. One of

  18. Microstructure and wear resistance of spray-formed supermartensitic stainless steel

    Directory of Open Access Journals (Sweden)

    Guilherme Zepon

    2013-06-01

    Full Text Available Since the early 90's the oil industry has been encouraging the development of corrosion and wear resistant alloys for onshore and offshore pipeline applications. In this context supermartensitic stainless steel was introduced to replace the more expensive duplex stainless steel for tubing applications. Despite the outstanding corrosion resistance of stainless steels, their wear resistance is of concern. Some authors reported obtaining material processed by spray forming, such as ferritic stainless steel, superduplex stainless steel modified with boron, and iron-based amorphous alloys, which presented high wear resistance while maintaining the corrosion performance1,2. The addition of boron to iron-based alloys promotes the formation of hard boride particles (M2B type which improve their wear resistances3-9. This work aimed to study the microstructure and wear resistance of supermartensitic stainless steel modified with 0.3 wt. (% and 0.7 wt. (% processed by spray forming (SF-SMSS 0.3%B and SF-SMSS 0.7%B, respectively. These boron contents were selected in order to improve the wear resistance of supermartensitic stainless steel through the formation of uniformly distributed borides maintaining the characteristics of the corrosion resistant matrix. SF-SMSS 0.7%B presents an abrasive wear resistance considerably higher than spray-formed supermartensitic stainless steel without boron addition (SF-SMSS.

  19. Multivariate return periods of sea storms for coastal erosion risk assessment

    Directory of Open Access Journals (Sweden)

    S. Corbella

    2012-08-01

    Full Text Available The erosion of a beach depends on various storm characteristics. Ideally, the risk associated with a storm would be described by a single multivariate return period that is also representative of the erosion risk, i.e. a 100 yr multivariate storm return period would cause a 100 yr erosion return period. Unfortunately, a specific probability level may be associated with numerous combinations of storm characteristics. These combinations, despite having the same multivariate probability, may cause very different erosion outcomes. This paper explores this ambiguity problem in the context of copula based multivariate return periods and using a case study at Durban on the east coast of South Africa. Simulations were used to correlate multivariate return periods of historical events to return periods of estimated storm induced erosion volumes. In addition, the relationship of the most-likely design event (Salvadori et al., 2011 to coastal erosion was investigated. It was found that the multivariate return periods for wave height and duration had the highest correlation to erosion return periods. The most-likely design event was found to be an inadequate design method in its current form. We explore the inclusion of conditions based on the physical realizability of wave events and the use of multivariate linear regression to relate storm parameters to erosion computed from a process based model. Establishing a link between storm statistics and erosion consequences can resolve the ambiguity between multivariate storm return periods and associated erosion return periods.

  20. Using rare earth element tracers and neutron activation analysis to study rill erosion process

    International Nuclear Information System (INIS)

    Li Mian; Li Zhanbin; Ding Wengfeng; Liu Puling; Yao Wenyi

    2006-01-01

    Spatially averaged soil erosion data provide little information on the process of rill erosion. The dynamically varied data on the temporal and spatial distributions in the rill erosion process are needed to better understand the erosion process and reveal its innate characteristics. The objectives of this study were to examine the feasibility and effectiveness of rare earth element (REE) tracers and the neutron activation analysis (NAA) method on the study of the rill erosion process and to reveal quantitatively the relationships and characteristics of temporal and spatial distributions of sediment yield in rill erosion. Four REEs were used to study the changeable process of rill erosion at 4 slope positions. Four water inflow rates were applied to a 0.3x5 m soil bed at 3 slopes of 10.5%, 15.8% and 21.2% in scouring experiments. All of the runoff was collected in the experiment. Each sample was air-dried and well mixed. Then 20 g of each sample was sieved through 100-mesh and about a 50 mg sample was weighed for analysis of the four elemental compositions by NAA. Results indicate that the REE tracers and NAA method can be used to not only quantitatively determine soil erosion amounts on different slope segments, but also to reveal the changeable process of rill erosion amount. All of the relative errors of the experimental results were less than 25%, which is considered satisfactory on the study of rill erosion process

  1. Using rare earth element tracers and neutron activation analysis to study rill erosion process

    Energy Technology Data Exchange (ETDEWEB)

    Li Mian [Yellow River Institute of Hydraulic Research, Yellow River Conservancy Commission, Key Laboratory of Yellow River Sediment Research of Ministry of Water Resources, Shunhelu 45, Zhengzhou, Henan 450003 (China)]. E-mail: hnli-mian@163.com; Li Zhanbin [Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Ding Wengfeng [Institute of Soil and Water Conservation, Yangtse River' s Scientific Research Institute, Wuhan, Hubei 430010 (China); Liu Puling [Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Yao Wenyi [Yellow River Institute of Hydraulic Research, Yellow River Conservancy Commission, Key Laboratory of Yellow River Sediment Research of Ministry of Water Resources, Shunhelu 45, Zhengzhou, Henan 450003 (China)

    2006-03-15

    Spatially averaged soil erosion data provide little information on the process of rill erosion. The dynamically varied data on the temporal and spatial distributions in the rill erosion process are needed to better understand the erosion process and reveal its innate characteristics. The objectives of this study were to examine the feasibility and effectiveness of rare earth element (REE) tracers and the neutron activation analysis (NAA) method on the study of the rill erosion process and to reveal quantitatively the relationships and characteristics of temporal and spatial distributions of sediment yield in rill erosion. Four REEs were used to study the changeable process of rill erosion at 4 slope positions. Four water inflow rates were applied to a 0.3x5 m soil bed at 3 slopes of 10.5%, 15.8% and 21.2% in scouring experiments. All of the runoff was collected in the experiment. Each sample was air-dried and well mixed. Then 20 g of each sample was sieved through 100-mesh and about a 50 mg sample was weighed for analysis of the four elemental compositions by NAA. Results indicate that the REE tracers and NAA method can be used to not only quantitatively determine soil erosion amounts on different slope segments, but also to reveal the changeable process of rill erosion amount. All of the relative errors of the experimental results were less than 25%, which is considered satisfactory on the study of rill erosion process.

  2. Residual Stresses and Sliding Wear.

    Science.gov (United States)

    1982-05-25

    case of rolling contact, taking into account strain hardening during plastic deformation. ..-s calculations (forSAE 52100 at a hardness level of 58.5 R...can reach -800- 1000 MPa. If 033 was comparable to these values, it would indeed effect the wear rate. It is evident that an experimental deter...cc o 40 1 °2 00 I I +A ) S l~lll0 44MUK I CQ E3 e0 El 0 Uc 00 E3 (3 80 j40 c (vclq) SSHHI +ce ce mCQ ce (2E e0 4El EJ) E - 0 El 0 E0 .. t El 0 (vdNp

  3. Gastric Mucosal Erosions - Radiologic evaluation -

    International Nuclear Information System (INIS)

    Kim, Seung Hyup

    1985-01-01

    70 cases of gastric mucosal erosions were diagnosed by double contrast upper gastrointestinal examinations and endoscopic findings. Analyzing the radiologic findings of these 70 cases of gastric mucosal erosions, the following results were obtained. 1. Among the total 70 cases, 65 cases were typical varioliform erosions showing central depressions and surrounding mucosal elevations. Remaining 5 cases were erosions of acute phase having multiple irregular depressions without surrounding elevations. 2. The gastric antrum was involved alone or in part in all cases. Duodenal bulb was involved with gastric antrum in 4 cases. 3. The majority of the cases had multiple erosions. There were only 2 cases of single erosion. 4. In 65 cases of varioliform erosions; 1) The diameter of the surrounding elevations varied from 3 to 20 mm with the majority (47 cases) between 6 and 10 mm. 2) In general, the surrounding elevations with sharp margin on double contrast films were also clearly demonstrated on compression films but those with faint margin were not. 3) The size of the central barium collections varied from pinpoint to 10 mm with the majority under 5 mm. The shape of the central barium collections in majority of the cases were round with a few cases of linear, triangular or star-shape. 5. In 5 cases of acute phase erosions; 1) All the 5 cases were females. 2) On double contrast radiography, all the cases showed multiple irregular depressed lesions without surrounding elevations. 3) 1 case had the history of hematemesis. 4) In 1 case, there was marked radiological improvement on follow-up study of 2 months interval. 6. In 23 cases, there were coexistent diseases with gastric mucosal erosions. These were 13 cases of duodenal bulb ulcers,7 cases of benign gastric ulcers and 3 others

  4. Modeling wear of cast Ti alloys.

    Science.gov (United States)

    Chan, Kwai S; Koike, Marie; Okabe, Toru

    2007-05-01

    The wear behavior of Ti-based alloys was analyzed by considering the elastic-plastic fracture of individual alloys in response to the relevant contact stress field. Using the contact stresses as the process driving force, wear was computed as the wear rate or volume loss as a function of hardness and tensile ductility for Ti-based cast alloys containing an alpha, alpha+beta or beta microstructure with or without the intermetallic precipitates. Model predictions indicated that wear of Ti alloys increases with increasing hardness but with decreasing fracture toughness or tensile ductility. The theoretical results are compared with experimental data to elucidate the roles of microstructure in wear and contrasted against those in grindability.

  5. The friction wear of electrolytic composite coatings

    International Nuclear Information System (INIS)

    Starosta, R.

    2002-01-01

    The article presents the results of investigation of wear of galvanic composite coatings Ni-Al 2 O 3 and Ni-41%Fe-Al 2 O 3 . The diameter of small parts of aluminium oxide received 0.5; 3; 5 μm. Investigations of friction sliding were effected on PT3 device at Technical University of Gdansk. Counter sample constituted a funnel made of steel NC6 (750 HV). Increase of wear coatings together with the rise of iron content in matrix is observed. The rise of sizes of ceramic particles caused decrease of wear of composite coatings, but rise of steel funnel wear. The friction coefficient increased after ceramic particle s were built in coatings. The best wear resistance characterized Ni-41%Fe-Al 2 O 3 coatings containing 2.2x10 6 mm -2 ceramic particles. (author)

  6. Tool Wear Monitoring Using Time Series Analysis

    Science.gov (United States)

    Song, Dong Yeul; Ohara, Yasuhiro; Tamaki, Haruo; Suga, Masanobu

    A tool wear monitoring approach considering the nonlinear behavior of cutting mechanism caused by tool wear and/or localized chipping is proposed, and its effectiveness is verified through the cutting experiment and actual turning machining. Moreover, the variation in the surface roughness of the machined workpiece is also discussed using this approach. In this approach, the residual error between the actually measured vibration signal and the estimated signal obtained from the time series model corresponding to dynamic model of cutting is introduced as the feature of diagnosis. Consequently, it is found that the early tool wear state (i.e. flank wear under 40µm) can be monitored, and also the optimal tool exchange time and the tool wear state for actual turning machining can be judged by this change in the residual error. Moreover, the variation of surface roughness Pz in the range of 3 to 8µm can be estimated by the monitoring of the residual error.

  7. Biologically Based Restorative Management of Tooth Wear

    Directory of Open Access Journals (Sweden)

    Martin G. D. Kelleher

    2012-01-01

    Full Text Available The prevalence and severity of tooth wear is increasing in industrialised nations. Yet, there is no high-level evidence to support or refute any therapeutic intervention. In the absence of such evidence, many currently prevailing management strategies for tooth wear may be failing in their duty of care to first and foremost improve the oral health of patients with this disease. This paper promotes biologically sound approaches to the management of tooth wear on the basis of current best evidence of the aetiology and clinical features of this disease. The relative risks and benefits of the varying approaches to managing tooth wear are discussed with reference to long-term follow-up studies. Using reference to ethical standards such as “The Daughter Test”, this paper presents case reports of patients with moderate-to-severe levels of tooth wear managed in line with these biologically sound principles.

  8. Predicting railway wheel wear under uncertainty of wear coefficient, using universal kriging

    International Nuclear Information System (INIS)

    Cremona, Marzia A.; Liu, Binbin; Hu, Yang; Bruni, Stefano; Lewis, Roger

    2016-01-01

    Railway wheel wear prediction is essential for reliability and optimal maintenance strategies of railway systems. Indeed, an accurate wear prediction can have both economic and safety implications. In this paper we propose a novel methodology, based on Archard's equation and a local contact model, to forecast the volume of material worn and the corresponding wheel remaining useful life (RUL). A universal kriging estimate of the wear coefficient is embedded in our method. Exploiting the dependence of wear coefficient measurements with similar contact pressure and sliding speed, we construct a continuous wear coefficient map that proves to be more informative than the ones currently available in the literature. Moreover, this approach leads to an uncertainty analysis on the wear coefficient. As a consequence, we are able to construct wear prediction intervals that provide reasonable guidelines in practice. - Highlights: • Wear prediction is of outmost importance for reliability of railway systems. • Wear coefficient is essential in prediction through Archard's equation. • A novel methodology is developed to predict wear and RUL. • Universal kriging is used for wear coefficient and uncertainty estimation. • A simulation study and a real case application are provided.

  9. Buffer erosion in dilute groundwater

    International Nuclear Information System (INIS)

    Schatz, T.; Kanerva, N.; Martikainen, J.; Sane, P.; Olin, M.; Seppaelae, A.; Koskinen, K.

    2013-08-01

    One scenario of interest for repository safety assessment involves the loss of bentonite buffer material in contact with dilute groundwater flowing through a transmissive fracture interface. In order to examine the extrusion/erosion behavior of bentonite buffer material under such circumstances, a series of experiments were performed in a flow-through, 1 mm aperture, artificial fracture system. These experiments covered a range of solution chemistry (salt concentration and composition), material composition (sodium montmorillonite and admixtures with calcium montmorillonite), and flow velocity conditions. No erosion was observed for sodium montmorillonite against solution compositions from 0.5 g/L to 10 g/L NaCl. No erosion was observed for 50/50 calcium/sodium montmorillonite against 0.5 g/L NaCl. Erosion was observed for both sodium montmorillonite and 50/50 calcium/sodium montmorillonite against solution compositions ≤ 0.25 g/L NaCl. The calculated erosion rates for the tests with the highest levels of measured erosion, i.e., the tests run under the most dilute conditions (ionic strength (IS) < ∼1 mM), were well-correlated to flow velocity, whereas the calculated erosion rates for the tests with lower levels of measured erosion, i.e., the tests run under somewhat less dilute conditions (∼1 mM < IS < ∼4 mM), were not similarly correlated indicating that material and solution composition can significantly affect erosion rates. In every experiment, both erosive and non-erosive, emplaced buffer material extruded into the fracture and was observed to be impermeable to water flowing in the fracture effectively forming an extended diffusive barrier around the intersecting fracture/buffer interface. Additionally, a model which was developed previously to predict the rate of erosion of bentonite buffer material in low ionic strength water in rock fracture environments was applied to three different cases: sodium montmorillonite expansion in a vertical tube, a

  10. Dynamic SEM wear studies of tungsten carbide cermets. [friction and wear experiments

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  11. Dental wear, wear rate, and dental disease in the African apes.

    Science.gov (United States)

    Elgart, Alison A

    2010-06-01

    The African apes possess thinner enamel than do other hominoids, and a certain amount of dentin exposure may be advantageous in the processing of tough diets eaten by Gorilla. Dental wear (attrition plus abrasion) that erodes the enamel exposes the underlying dentin and creates additional cutting edges at the dentin-enamel junction. Hypothetically, efficiency of food processing increases with junction formation until an optimal amount is reached, but excessive wear hinders efficient food processing and may lead to sickness, reduced fecundity, and death. Occlusal surfaces of molars and incisors in three populations each of Gorilla and Pan were videotaped and digitized. The quantity of incisal and molar occlusal dental wear and the lengths of dentin-enamel junctions were measured in 220 adult and 31 juvenile gorilla and chimpanzee skulls. Rates of dental wear were calculated in juveniles by scoring the degree of wear between adjacent molars M1 and M2. Differences were compared by principal (major) axis analysis. ANOVAs compared means of wear amounts. Pearson correlation coefficients were calculated to compare the relationship between molar wear and incidence of dental disease. Results indicate that quantities of wear are significantly greater in permanent incisors and molars and juvenile molars of gorillas compared to chimpanzees. The lengths of dentin-enamel junctions were predominantly suboptimal. Western lowland gorillas have the highest quantities of wear and the most molars with suboptimal wear. The highest rates of wear are seen in Pan paniscus and Pan t. troglodytes, and the lowest rates are found in P.t. schweinfurthii and G. g. graueri. Among gorillas, G. b. beringei have the highest rates but low amounts of wear. Coefficients between wear and dental disease were low, but significant when all teeth were combined. Gorilla teeth are durable, and wear does not lead to mechanical senescence in this sample.

  12. Prevalence of dental erosion among 18-year-old adolescents in the borderland districts of Lviv (Ukraine) and Lublin (Poland).

    Science.gov (United States)

    Bachanek, Teresa; Hendzel, Barbara; Wolańska, Ewa; Szybinsky, Volodymir; Ogonovsky, Roman; Hrynovets, Volodymir; Samborski, Dariusz; Nakonieczna-Rudnicka, Marta; Chałas, Renata

    2018-03-14

    Recent epidemiological studies have shown an association between dental erosion occurrence and changes in lifestyle and dietary habits in both developed and developing countries, and now affects different regions of the world. Furthermore, in current literature, studies have shown that the prevalence of erosive tooth wear has increased particularly among the younger population. The aim of the study was to assess the prevalence and severity of erosive tooth wear among 18-year-old adolescents in the districts of Lviv (Ukraine) and Lublin (Poland). College students (254 subjects) aged 18, living in the Lviv and Lublin districts were examined. Erosive lesions presented in the teeth were assessed on the basis of the BEWE (Basic Erosive Wear Examination) index. Among the 137 patients living in the Lublin district, 70 were females and 67 were males, while in the Lviv district, 60 women and 57 men were examined. In both districts, the following numbers of rural patients were examined: 66 in Lublin district and 56 in Lviv district; for urban inhabitants, the numbers were 71 in Lublin and 61 in Lviv. Analysing the BEWE values, it was noted that higher BEWE values, and resulting from them significant differences were observed in both male and female groups living in Lublin, compared with Lviv inhabitants. Based on clinical examination and statistical analysis, the occurrence of lesions of an erosive character in at least one sextant were observed in 59.85% of patients from Lublin district, and in 42.74% of patients from Lviv district. On the basis of the conducted study in the Polish and Ukrainian groups of 18-year-old adolescents living on the borderland, it can be stated that dental erosion is a problem noticeable in both groups of cohorts, but with higher prevalence in the Lublin district.

  13. In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel.

    Science.gov (United States)

    Lepri, Taísa Penazzo; Scatolin, Renata Siqueira; Colucci, Vivian; De Alexandria, Adílis Kalina; Maia, Lucianne Cople; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

    2014-08-01

    The present study aimed to evaluate in situ the effect of CO2 laser irradiation to control the progression of enamel erosive lesions. Fifty-six slabs of bovine incisors enamel (5 × 3 × 2.5 mm(3) ) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO2 laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO2 laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2-day lead-in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross-over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three-way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO2 laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO2 laser irradiation was performed. There was no difference in enamel wear between specimens CO2 -laser irradiated and non-irradiated (P = 0.513). Under intraoral conditions, CO2 laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. © 2014 Wiley Periodicals, Inc.

  14. Design Mixers to Minimize Effects of Erosion and Corrosion Erosion

    Directory of Open Access Journals (Sweden)

    Julian Fasano

    2012-01-01

    Full Text Available A thorough review of the major parameters that affect solid-liquid slurry wear on impellers and techniques for minimizing wear is presented. These major parameters include (i chemical environment, (ii hardness of solids, (iii density of solids, (iv percent solids, (v shape of solids, (vi fluid regime (turbulent, transitional, or laminar, (vii hardness of the mixer's wetted parts, (viii hydraulic efficiency of the impeller (kinetic energy dissipation rates near the impeller blades, (ix impact velocity, and (x impact frequency. Techniques for minimizing the wear on impellers cover the choice of impeller, size and speed of the impeller, alloy selection, and surface coating or coverings. An example is provided as well as an assessment of the approximate life improvement.

  15. Effect of flow velocity on erosion-corrosion behaviour of QSn6 alloy

    Science.gov (United States)

    Huang, Weijiu; Zhou, Yongtao; Wang, Zhenguo; Li, Zhijun; Zheng, Ziqing

    2018-05-01

    The erosion-corrosion behaviour of QSn6 alloy used as propellers in marine environment was evaluated by erosion-corrosion experiments with/without cathodic protection, electrochemical tests and scanning electron microscope (SEM) observations. The analysis was focused on the effect of flow velocity. The dynamic polarization curves showed that the corrosion rate of the QSn6 alloy increased as the flow velocity increased, due to the protective surface film removal at higher velocities. The lowest corrosion current densities of 1.26 × 10‑4 A cm‑2 was obtained at the flow velocity of 7 m s‑1. Because of the higher particle kinetic energies at higher flow velocity, the mass loss rate of the QSn6 alloy increased as the flow velocity increased. The mass loss rate with cathodic protection was lower than that without cathodic protection under the same conditions. Also, the lowest mass loss rate of 0.7 g m‑2 · h‑1 was acquired at the flow velocity of 7 m s‑1 with cathodic protection. However, the increase rate of corrosion rate and mass loss were decreased with increasing the flow velocity. Through observation the SEM morphologies of the worn surfaces, the main wear mechanism was ploughing with/without cathodic protection. The removal rates of the QSn6 alloy increased as the flow velocity increased in both pure erosion and erosion-corrosion, whereas the erosion and corrosion intensified each other. At the flow velocity of 7 m s‑1, the synergy rate (ΔW) exceeded by 5 times the erosion rate (Wwear). Through establishment and observation the erosion-corrosion mechanism map, the erosion-corrosion was the dominant regime in the study due to the contribution of erosion on the mass loss rate exceeded the corrosion contribution. The QSn6 alloy with cathodic protection is feasible as propellers, there are higher security at lower flow velocity, such as the flow velocity of 7 m s‑1 in the paper.

  16. Mechanical properties and three-body wear of dental restoratives and their comparative flowable materials.

    Science.gov (United States)

    Schultz, Sabine; Rosentritt, Martin; Behr, Michael; Handel, Gerhard

    2010-01-01

    To compare wear performance and resistance to crack propagation (K1C) of commercial restorative materials and their flowable variations. A potential correlation between three-body wear and fracture toughness, modulus of elasticity, fracture work, Vickers hardness, and filler content was investigated. Seven restoratives (five composites, one ormocer, and one compomer) and their corresponding flowable materials were used to determine and compare the three-body wear with a bolus of millet-seed shells and rice food (Willytec). The wear characteristics were measured by profilometry after 50,000, 100,000, 150,000, and 200,000 loading cycles. The fracture toughness value, K1C (MPam1/2), for each single-edged notched specimen was measured in a three-point bending test (universal testing machine 1446, Zwick). Fracture work and modulus of elasticity were calculated from the load curves. Vickers hardness was measured (HV hardness tester, Zwick) according to DIN 50133. The veneering composite Sinfony (3M ESPE) was used as a reference material. Heavily filled composites experienced less wear than their flowable variations. The nanofiller composites revealed better wear results than hybrid composites, compomers, and ormocers. After 200,000 load cycles, the lowest wear rates were detected for Grandio (14 microm; Voco), and the highest mean values were found for Dyract AP (104 microm; Dentsply DeTrey). The values for fracture toughness (K1C) ranged from 0.82 to 3.64 MPam1/2. Highest K1C data was exhibited by the nanocomposite Nanopaq (Schutz Dental). All tested restorative materials exhibited higher fracture toughness than their low-viscosity variations. The wear resistance of the newer generation composites with incorporated nanofiller or microfiller particles increased to a high extent. Flowables show less resistance against wear and crack propagation because of their lower filler content. The reduced mechanical properties limit their use as a restorative to small noncontact

  17. Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool

    Directory of Open Access Journals (Sweden)

    Jose Mario Paiva

    2018-02-01

    Full Text Available In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,AlN deposited by physical vapor deposition (PVD have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC and one central rotating cathode (CERC. The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES, scanning electron microscopy (SEM, and X-ray diffraction (XRD, respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

  18. Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool.

    Science.gov (United States)

    Paiva, Jose Mario; Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Seid Ahmed, Yassmin; Matos Martins, Marcelo; Bork, Carlos; Veldhuis, Stephen

    2018-02-28

    In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si₃N₄ nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

  19. Single-crystal-silicon-based microinstrument to study friction and wear at MEMS sidewall interfaces

    International Nuclear Information System (INIS)

    Ansari, N; Ashurst, W R

    2012-01-01

    Since the advent of microelectromechanical systems (MEMS) technology, friction and wear are considered as key factors that determine the lifetime and reliability of MEMS devices that contain contacting interfaces. However, to date, our knowledge of the mechanisms that govern friction and wear in MEMS is insufficient. Therefore, systematically investigating friction and wear at MEMS scale is critical for the commercial success of many potential MEMS devices. Specifically, since many emerging MEMS devices contain more sidewall interfaces, which are topographically and chemically different from in-plane interfaces, studying the friction and wear characteristics of MEMS sidewall surfaces is important. The microinstruments that have been used to date to investigate the friction and wear characteristics of MEMS sidewall surfaces possess several limitations induced either by their design or the structural film used to fabricate them. Therefore, in this paper, we report on a single-crystal-silicon-based microinstrument to study the frictional and wear behavior of MEMS sidewalls, which not only addresses some of the limitations of other microinstruments but is also easy to fabricate. The design, modeling and fabrication of the microinstrument are described in this paper. Additionally, the coefficients of static and dynamic friction of octadecyltrichlorosilane-coated sidewall surfaces as well as sidewall surfaces with only native oxide on them are also reported in this paper. (paper)

  20. Erosion-resistant composite material

    Science.gov (United States)

    Finch, C.B.; Tennery, V.J.; Curlee, R.M.

    A highly erosion-resistant composite material is formed of chemical vapor-deposited titanium diboride on a sintered titanium diboride-nickel substrate. This material may be suitable for use in cutting tools, coal liquefaction systems, etc.

  1. Microstructure and wear behaviour of aluminium alloys containing embedded nanoscaled lead dispersoids

    International Nuclear Information System (INIS)

    Bhattacharya, Victoria; Chattopadhyay, K.

    2004-01-01

    We report the early stage friction and wear characteristics of aluminium containing nanosized lead dispersions. The nanocomposite was produced by rapid solidification. The experimental results indicate a significant decrease in friction and wear rate in comparison to its coarse grained counterparts. We show that the observed results suggest an adhesive type of wear mechanism. However, increase in hardness due to refinement of the aluminium grains cannot quantitatively rationalize the results. We explore and discuss the role of nanoscaled lead particles and the mass transport between the sample and counterface via mechanical alloying, in the formation of tribolayers affecting the tribological properties. The plane view and cross-sectional transmission electron microscopy reveals significant elongation as well as coarsening of the lead particles during the process of wear. We attempt to understand these results in the framework of moving dislocations and their assistance to the mass transport among the dispersed lead particles

  2. Wear life of sputtered MoSx films extended by high energy ion implantation

    International Nuclear Information System (INIS)

    Okazaki, Yasufumi; Fujiura, Hideo; Nishimura, Makoto

    2000-01-01

    The tribological characteristics of sputtered MoSx films have been reportedly improved by inert gas ion implantation. We tried to extend their wear life by introducing indium, carbon and gallium ion implantation. Pin-on-disk testers were used to measure friction coefficient and wear life in a vacuum, dry and humid air. Comparing with the unimplanted films, we found that the indium ion implanted films showed marked improvement in wear life in a vacuum. Carbon ion implanted films showed improvement in wear life in high humid air. Implantation was effective when it was conducted with maximum concentration at the interface between film and substrate rather than at the neighborhood of the interface inside a film. (author)

  3. Soil Erosion and Agricultural Sustainability

    Science.gov (United States)

    Montgomery, D. R.

    2009-04-01

    Data drawn from a global compilation of studies support the long articulated contention that erosion rates from conventionally plowed agricultural fields greatly exceed rates of soil production, erosion under native vegetation, and long-term geological erosion. Whereas data compiled from around the world show that soil erosion under conventional agriculture exceeds both rates of soil production and geological erosion rates by up to several orders of magnitude, similar global distributions of soil production and geological erosion rates suggest an approximate balance. Net soil erosion rates in conventionally plowed fields on the order of 1 mm/yr can erode typical hillslope soil profiles over centuries to millennia, time-scales comparable to the longevity of major civilizations. Well-documented episodes of soil loss associated with agricultural activities date back to the introduction of erosive agricultural methods in regions around the world, and stratigraphic records of accelerated anthropogenic soil erosion have been recovered from lake, fluvial, and colluvial stratigraphy, as well as truncation of soil stratigraphy (such as truncated A horizons). A broad convergence in the results from studies based on various approaches employed to study ancient soil loss and rates of downstream sedimentation implies that widespread soil loss has accompanied human agricultural intensification in examples drawn from around the world. While a broad range of factors, including climate variability and society-specific social and economic contexts — such as wars or colonial relationships — all naturally influence the longevity of human societies, the ongoing loss of topsoil inferred from studies of soil erosion rates in conventional agricultural systems has obvious long-term implications for agricultural sustainability. Consequently, modern agriculture — and therefore global society — faces a fundamental question over the upcoming centuries. Can an agricultural system

  4. Severe tooth wear in Prader-Willi syndrome. A case-control study.

    Science.gov (United States)

    Saeves, Ronnaug; Espelid, Ivar; Storhaug, Kari; Sandvik, Leiv; Nordgarden, Hilde

    2012-05-28

    Prader-Willi syndrome (PWS) is a rare complex multsystemic genetic disorder characterized by severe neonatal hypotonia, endocrine disturbances, hyperphagia and obesity, mild mental retardation, learning disabilities, facial dysmorphology and oral abnormalities. The purpose of the present study was to explore the prevalence of tooth wear and possible risk factors in individuals with Prader-Willi syndrome. Forty-nine individuals (6-40 years) with PWS and an age- and sex-matched control group were included. Tooth wear was evaluated from dental casts and intraoral photographs and rated by four examiners using the Visual Erosion Dental Examination (VEDE) scoring system and the individual tooth wear index IA. In accordance with the VEDE scoring system, tooth wear was also evaluated clinically. Whole saliva was collected. Mean VEDE score was 1.70 ± 1.44 in the PWS group and 0.46 ± 0.36 in the control group (p Prader-Willi syndrome. There is therefore considerable need for prosthodontic rehabilitation in young adults with PWS.

  5. New perspectives on the soil erosion-soil quality relationship

    International Nuclear Information System (INIS)

    Pennock, D.J.

    1998-01-01

    The redistribution of soil has a profound impact on its quality (defined as its ability to function within its ecosystem and within adjacent ecosystems) and ultimately on its productivity for crop growth. The application of 137 Cs-redistribution techniques to the study of erosion has yielded major new insights into the soil erosion-soil quality relationship. In highly mechanized agricultural systems, tillage erosion can be the dominant cause of soil redistribution; in other agroecosystems, wind and water erosion dominate. Each causal factor results in characteristic landscape-scale patterns of redistribution. In landscapes dominated by tillage redistribution, highest losses occur in shoulder positions (those with convex downslope curvatures); in water-erosion-dominated landscapes, highest losses occur where slope gradient and length are at a maximum. Major impacts occur through the loss of organically-enriched surface material and through the incorporation of possibly yield-limiting subsoils into the rooting zone of the soil column. The potential impact of surface soil losses and concomitant subsoil incorporation on productivity may be assessed by examining the pedological nature of the affected soils and their position in the landscape. The development of sound conservation policies requires that the soil erosion-quality relationship be rigorously examined in the full range of pedogenic environments, and future applications of the 137 Cs technique hold considerable promise for providing this comprehensive global database. (author)

  6. Erosion properties of unipolar arcs

    International Nuclear Information System (INIS)

    Chekalin, Eh.K.

    1982-01-01

    Processes modelling the formation of unipolar arcs on the elements of the first wall in limiters of the vacuum chamber and on active elements of tokamak divertor, are experimentally investigated. Erosion, processes that take place at two types of non-stationary cathode spots are considered. Experimental data prove the possibility of reducing erosion intensity by coating the surface of electrodes by oxide films, reduction of the temperature of electrode and discharge current

  7. Investigation of erosion behavior in different pipe-fitting using Eulerian-Lagrangian approach

    Science.gov (United States)

    Kulkarni, Harshwardhan; Khadamkar, Hrushikesh; Mathpati, Channamallikarjun

    2017-11-01

    Erosion is a wear mechanism of piping system in which wall thinning occurs because of turbulent flow along with along with impact of solid particle on the pipe wall, because of this pipe ruptures causes costly repair of plant and personal injuries. In this study two way coupled Eulerian-Lagrangian approach is used to solve the liquid solid (water-ferrous suspension) flow in the different pipe fitting namely elbow, t-junction, reducer, orifice and 50% open gate valve. Simulations carried out using incomressible transient solver in OpenFOAM for different Reynolds's number (10k, 25k, 50k) and using WenYu drag model to find out possible higher erosion region in pipe fitting. Used transient solver is a hybrid in nature which is combination of Lagrangian library and pimpleFoam. Result obtained from simulation shows that exit region of elbow specially downstream of straight, extradose of the bend section more affected by erosion. Centrifugal force on solid particle at bend affect the erosion behavior. In case of t-junction erosion occurs below the locus of the projection of branch pipe on the wall. For the case of reducer, orifice and a gate valve reduction area as well as downstream is getting more affected by erosion because of increase in velocities.

  8. Detecting Anthropogenic Disturbance on Weathering and Erosion Processes

    Science.gov (United States)

    Vanacker, V.; Schoonejans, J.; Bellin, N.; Ameijeiras-Mariño, Y.; Opfergelt, S.; Christl, M.

    2014-12-01

    Anthropogenic disturbance of natural vegetation can profoundly alter the physical, chemical and biological processes within soils. Rapid removal of topsoil during intense farming can result in an imbalance between soil production through chemical weathering and physical erosion, with direct implications on local biogeochemical cycling. However, the feedback mechanisms between soil erosion, chemical weathering and biogeochemical cycling in response to anthropogenic forcing are not yet fully understood. In this paper, we analyze dynamic soil properties for a rapidly changing anthropogenic landscape in the Spanish Betic Cordillera; and focus on the coupling between physical erosion, soil production and soil chemical weathering. Modern erosion rates were quantified through analysis of sediment deposition volumes behind check dams, and represent catchment-average erosion rates over the last 10 to 50 years. Soil production rates are derived from in-situ produced 10Be nuclide concentrations, and represent long-term flux rates. In each catchment, soil chemical weathering intensities were calculated for two soil-regolith profiles. Although Southeast Spain is commonly reported as the European region that is most affected by land degradation, modern erosion rates are low (140 t ha-1 yr-1). About 50 % of the catchments are losing soils at a rate of less than 60 t km-2 yr-1. Our data show that modern erosion rates are roughly of the same magnitude as the long-term or cosmogenically-derived erosion rates in the Betic Cordillera. Soils developed on weathered metamorphic rocks have no well-developed profile characteristics, and are generally thin and stony. Nevertheless, soil chemical weathering intensities are high; and question the occurrence of past soil truncation.

  9. Automated visual inspection of brake shoe wear

    Science.gov (United States)

    Lu, Shengfang; Liu, Zhen; Nan, Guo; Zhang, Guangjun

    2015-10-01

    With the rapid development of high-speed railway, the automated fault inspection is necessary to ensure train's operation safety. Visual technology is paid more attention in trouble detection and maintenance. For a linear CCD camera, Image alignment is the first step in fault detection. To increase the speed of image processing, an improved scale invariant feature transform (SIFT) method is presented. The image is divided into multiple levels of different resolution. Then, we do not stop to extract the feature from the lowest resolution to the highest level until we get sufficient SIFT key points. At that level, the image is registered and aligned quickly. In the stage of inspection, we devote our efforts to finding the trouble of brake shoe, which is one of the key components in brake system on electrical multiple units train (EMU). Its pre-warning on wear limitation is very important in fault detection. In this paper, we propose an automatic inspection approach to detect the fault of brake shoe. Firstly, we use multi-resolution pyramid template matching technology to fast locate the brake shoe. Then, we employ Hough transform to detect the circles of bolts in brake region. Due to the rigid characteristic of structure, we can identify whether the brake shoe has a fault. The experiments demonstrate that the way we propose has a good performance, and can meet the need of practical applications.

  10. Effects of chemistry on corrosion-erosion of steels in water and wet steam

    International Nuclear Information System (INIS)

    Berge, P.; Ducreux, J.; Saint-Paul, P.

    1981-01-01

    In steam production plants, numerous cases of degradation of steels occur when in contact with water or wet steam circulating at high velocity: in feed or discharge pumps, water reheaters, etc. When the phenomenon occurs without any mechanical wear of the metal or the oxide from the impact of solid particles (abrasion) or droplets (erosion), it is called corrosion-erosion. The phenomenon usually occurs between 100 and 250 0 C, as has been confirmed by an empirical study of the thermal and hydraulic factors which govern it. Corrosion rates can reach 1 to 2 mm/year, for a carbon steel pipe where water treated with ammonia circulates at about pH 9, at 200 0 C, and at a velocity of 5 to 10 m/s. This study evaluates the part played by the factors solely connected to the chemistry of water, with respect to the kinetics of the corrosion-erosion phenomenon. (author)

  11. Wind erosion of soils burned by wildfire

    Science.gov (United States)

    N. S. Wagenbrenner; M. J. Germino; B. K. Lamb; R. B. Foltz; P. R. Robichaud

    2011-01-01

    Wind erosion and aeolian transport processes are largely unstudied in the post-wildfire environment, but recent studies have shown that wind erosion can play a major role in burned landscapes. A wind erosion monitoring system was installed immediately following a wildfire in southeastern Idaho, USA to measure wind erosion from the burned area (Figure 1). This paper...

  12. Gaussian process regression for tool wear prediction

    Science.gov (United States)

    Kong, Dongdong; Chen, Yongjie; Li, Ning

    2018-05-01

    To realize and accelerate the pace of intelligent manufacturing, this paper presents a novel tool wear assessment technique based on the integrated radial basis function based kernel principal component analysis (KPCA_IRBF) and Gaussian process regression (GPR) for real-timely and accurately monitoring the in-process tool wear parameters (flank wear width). The KPCA_IRBF is a kind of new nonlinear dimension-increment technique and firstly proposed for feature fusion. The tool wear predictive value and the corresponding confidence interval are both provided by utilizing the GPR model. Besides, GPR performs better than artificial neural networks (ANN) and support vector machines (SVM) in prediction accuracy since the Gaussian noises can be modeled quantitatively in the GPR model. However, the existence of noises will affect the stability of the confidence interval seriously. In this work, the proposed KPCA_IRBF technique helps to remove the noises and weaken its negative effects so as to make the confidence interval compressed greatly and more smoothed, which is conducive for monitoring the tool wear accurately. Moreover, the selection of kernel parameter in KPCA_IRBF can be easily carried out in a much larger selectable region in comparison with the conventional KPCA_RBF technique, which helps to improve the efficiency of model construction. Ten sets of cutting tests are conducted to validate the effectiveness of the presented tool wear assessment technique. The experimental results show that the in-process flank wear width of tool inserts can be monitored accurately by utilizing the presented tool wear assessment technique which is robust under a variety of cutting conditions. This study lays the foundation for tool wear monitoring in real industrial settings.

  13. Erosion-corrosion resistance properties of 316L austenitic stainless steels after low-temperature liquid nitriding

    Science.gov (United States)

    Zhang, Xiangfeng; Wang, Jun; Fan, Hongyuan; Pan, Dong

    2018-05-01

    The low-temperature liquid nitriding of stainless steels can result in the formation of a surface zone of so-called expanded austenite (S-phase) by the dissolution of large amounts of nitrogen in the solid solution and formation of a precipitate-free layer supersaturated with high hardness. Erosion-corrosion measurements were performed on low-temperature nitrided and non-nitrided 316L stainless steels. The total erosion-corrosion, erosion-only, and corrosion-only wastages were measured directly. As expected, it was shown that low-temperature nitriding dramatically reduces the degree of erosion-corrosion in stainless steels, caused by the impingement of particles in a corrosive medium. The nitrided 316L stainless steels exhibited an improvement of almost 84% in the erosion-corrosion resistance compared to their non-nitrided counterparts. The erosion-only rates and synergistic levels showed a general decline after low-temperature nitriding. Low-temperature liquid nitriding can not only reduce the weight loss due to erosion but also significantly reduce the weight loss rate of interactions, so that the total loss of material decreased evidently. Therefore, 316L stainless steels displayed excellent erosion-corrosion behaviors as a consequence of their highly favorable corrosion resistances and superior wear properties.

  14. Development of dynamic models of wagons on models 18-9810 and 18-9855 bogies taking into account wheel wear research

    Directory of Open Access Journals (Sweden)

    A. V. Saidova

    2013-04-01

    Full Text Available Purpose. Wear parameters clarification in wear simulation is an actual goal because of absence of corresponding data for freight cars in condition of using them on Russian railways. Research is devoted to development of dynamic models of wagons on three-peace two-axle models 18-9810 and 18-9855 bogies with maximum axle-loads 23,5 ts and 25 ts, and to choice of factors, with varying which parameters in the model of wheel wear can be identified. Methodology. The problem is solved by method of mathematic simulation in «MEDYNA» software. Wear calculation is based on abrasive wear theory (Archard’s theory. Findings. Clarification of wheels’ wear model may be done with varying of friction coefficient between wheel and rail for different wheel profile areas (flange and tread, wear coefficient in Archard’s model for mild and heavy wear and transition between them. Originality. Dynamic models of universal gondola on models 18-9810 and 18-9855 bogies are developed. It is established, that rail treads irregularities size effect wheel wear insignificantly, when car is running on circle track of constant radius. Practical value. Developed dynamic models of wagons on models 18-9810 and 18-9855 bogies may be used in wear simulation, determination of car running characteristics, interaction of car and rail of different type, construction, condition and etc. Research results of some factors influence on freight car wheel wear may be interesting for people, who study this problem.

  15. Estimating Wear Of Installed Ball Bearings

    Science.gov (United States)

    Keba, John E.; Mcvey, Scott E.

    1993-01-01

    Simple inspection and measurement technique makes possible to estimate wear of balls in ball bearing, without removing bearing from shaft on which installed. To perform measurement, one observes bearing cage while turning shaft by hand to obtain integral number of cage rotations and to measure, to nearest 2 degrees, number of shaft rotations producing cage rotations. Ratio between numbers of cages and shaft rotations depends only on internal geometry of bearing and applied load. Changes in turns ratio reflect changes in internal geometry of bearing provided measurements made with similar bearing loads. By assuming all wear occurs on balls, one computes effective value for this wear from change in turns ratio.

  16. Minimization of PWR reactor control rods wear

    International Nuclear Information System (INIS)

    Ponzoni Filho, Pedro; Moura Angelkorte, Gunther de

    1995-01-01

    The Rod Cluster Control Assemblies (RCCA's) of Pressurized Water Reactors (PWR's) have experienced a continuously wall cladding wear when Reactor Coolant Pumps (RCP's) are running. Fretting wear is a result of vibrational contact between RCCA rodlets and the guide cards which provide lateral support for the rodlets when RCCA's are withdrawn from the core. A procedure is developed to minimize the rodlets wear, by the shuffling and axial reposition of RCCA's every operating cycle. These shuffling and repositions are based on measurement of the rodlet cladding thickness of all RCCA's. (author). 3 refs, 2 figs, 2 tabs

  17. Tool wear modeling using abductive networks

    Science.gov (United States)

    Masory, Oren

    1992-09-01

    A tool wear model based on Abductive Networks, which consists of a network of `polynomial' nodes, is described. The model relates the cutting parameters, components of the cutting force, and machining time to flank wear. Thus real time measurements of the cutting force can be used to monitor the machining process. The model is obtained by a training process in which the connectivity between the network's nodes and the polynomial coefficients of each node are determined by optimizing a performance criteria. Actual wear measurements of coated and uncoated carbide inserts were used for training and evaluating the established model.

  18. Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk

    International Nuclear Information System (INIS)

    Wang, Song; Wang, Fei; Liao, Zhenhua; Wang, Qingliang; Liu, Yuhong; Liu, Weiqiang

    2015-01-01

    A ball-on-socket contact configuration was designed to simulate an artificial cervical disk in structure. UHMWPE (ultra high molecular weight polyethylene) hot pressed by powders and Ti6Al4V alloy were selected as the material combination of ball and socket. The socket surface was coated by a ~ 500 nm C-DLC (carbon ion implantation-diamond like carbon) mixed layer to improve its surface nano hardness and wear resistance. The torsional fretting wear behavior of the ball-on-socket model was tested at different angular displacements under 25% bovine serum lubrication with an axial force of 100 N to obtain more realistic results with that in vivo. The fretting running regimes and wear damage characteristics as well as wear mechanisms for both ball and socket were studied based on 2D (two dimension) optical microscope, SEM (scanning electron microscope) and 3D (three dimension) profiles. With the increase of angular displacement amplitude from 1° to 7°, three types of T-θ (Torsional torque-angular displacement amplitude) curves (i.e., linear, elliptical and parallelogram loops) corresponding to running regimes of PSR (partial slip regime), MR (mixed regime) and SR (slip regime) were observed and analyzed. Both the central region and the edge zone of the ball and socket were damaged. The worn surfaces were characterized by wear scratches and wear debris. In addition, more severe wear damage and more wear debris appeared on the central region of the socket at higher angular displacement amplitude. The dominant damage mechanism was a mix of surface scratch, adhesive wear and abrasive wear for the UHMWPE ball while that for the coated socket was abrasive wear by PE particles and some polishing and rolling process on the raised overgrown DLC grains. The frictional kinetic behavior, wear type, damage region and damage mechanism for the ball-on-socket model revealed significant differences with those of a ball-on-flat contact while showing better consistency with that of in

  19. Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Song [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Wang, Fei [School of Material Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Liao, Zhenhua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Wang, Qingliang [School of Material Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Liu, Yuhong [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liu, Weiqiang, E-mail: weiqliu@hotmail.com [Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2015-10-01

    A ball-on-socket contact configuration was designed to simulate an artificial cervical disk in structure. UHMWPE (ultra high molecular weight polyethylene) hot pressed by powders and Ti6Al4V alloy were selected as the material combination of ball and socket. The socket surface was coated by a ~ 500 nm C-DLC (carbon ion implantation-diamond like carbon) mixed layer to improve its surface nano hardness and wear resistance. The torsional fretting wear behavior of the ball-on-socket model was tested at different angular displacements under 25% bovine serum lubrication with an axial force of 100 N to obtain more realistic results with that in vivo. The fretting running regimes and wear damage characteristics as well as wear mechanisms for both ball and socket were studied based on 2D (two dimension) optical microscope, SEM (scanning electron microscope) and 3D (three dimension) profiles. With the increase of angular displacement amplitude from 1° to 7°, three types of T-θ (Torsional torque-angular displacement amplitude) curves (i.e., linear, elliptical and parallelogram loops) corresponding to running regimes of PSR (partial slip regime), MR (mixed regime) and SR (slip regime) were observed and analyzed. Both the central region and the edge zone of the ball and socket were damaged. The worn surfaces were characterized by wear scratches and wear debris. In addition, more severe wear damage and more wear debris appeared on the central region of the socket at higher angular displacement amplitude. The dominant damage mechanism was a mix of surface scratch, adhesive wear and abrasive wear for the UHMWPE ball while that for the coated socket was abrasive wear by PE particles and some polishing and rolling process on the raised overgrown DLC grains. The frictional kinetic behavior, wear type, damage region and damage mechanism for the ball-on-socket model revealed significant differences with those of a ball-on-flat contact while showing better consistency with that of in

  20. Investigation of the Degradation Mechanisms of Particulate Reinforced Epoxy Coatings and Zinc-Rich Coatings Under an Erosion and Corrosion Environment for Oil and Gas Industry Applications

    Science.gov (United States)

    Wang, Dailin

    During oil and gas production and transportation, the presence of an oil-sand slurry, together with the presence of CO2, H2S, oxygen, and seawater, create an erosive/abrasive and corrosive environment for the interior surfaces of undersea pipelines transporting oil and gas from offshore platforms. Erosion/wear and corrosion are often synergic processes leading to a much greater material loss of pipeline cross-section than that caused by each individual process alone. Both organic coatings and metallic sacrificial coatings have been widely employed to provide protection to the pipeline steels against corrosion through barrier protection and cathodic protection, and these protection mechanisms have been well studied. However, coating performance under the synergic processes of erosion/wear and corrosion have been much less researched and coating degradation mechanisms when erosion/wear and corrosion are both going on has not been well elucidated. In the work presented in this dissertation, steel panels coated with filler reinforced epoxy coatings and carbon nanotubes (CNTs) reinforced zinc-rich coatings have been evaluated under erosion/wear followed by an exposure to a corrosive environment. Electrochemical tests and material characterization methods have been applied to study the degradation mechanisms of the coatings during the tests and coating degradation mechanisms have been proposed. While organic coatings with a lower amount of filler particles provided better protection in a corrosive environment alone and in solid particle impingement erosion testing alone, organic coatings with a higher amount of filler particles showed better performance during wear testing alone. A higher amount of filler particles was also beneficial in providing protection against wear and corrosion environment, and erosion and corrosion environment. Coating thickness played a significant role in the barrier properties of the coatings under both erosion and corrosion tests. When the

  1. Erosion of marker coatings exposed to Pilot-PSI plasma

    NARCIS (Netherlands)

    Paris, P.; Hakola, A.; Bystrov, K.; De Temmerman, G.; Aints, M.; I. Jõgi,; Kiisk, M.; Kozlova, J.; Laan, M.; Likonen, J.; Lissovski, A.

    2013-01-01

    In this article, laser induced breakdown spectroscopy (LIBS) has been used to study plasma-induced erosion processes. Samples with ITER-relevant coatings were exposed to controlled plasma fluxes whose parameters were characteristic to those occurring in the reactor walls. After the experiments,

  2. Mechanisms of Degradation and Identification of Connectivity and Erosion Hotspots

    NARCIS (Netherlands)

    Hooke, J.; Sandercock, P.; Cammeraat, L.H.; Lesschen, J.P.; Borselli, L.; Torri, D.; Meerkerk, A.; van Wesemael, B.; Marchamalo, M.; Barbera, G.; Boix-Fayos, C.; Castillo, V.; Navarro-Cano, J.A.; Hooke, J.; Sandercock, P.

    2017-01-01

    The context of processes and characteristics of soil erosion and land degradation in Mediterranean lands is outlined. The concept of connectivity is explained. The remainder of the chapter demonstrates development of methods of mapping, analysis and modelling of connectivity to produce a spatial

  3. The Wearing Out of Genre Materials

    Science.gov (United States)

    Russ, Joanna

    1971-01-01

    Scenes and plots wear out in three distinct stages: Innocence, Plausibility, and Decadence. Examines westerns, spy stories, nurse novels, detective stories, science fiction, pornography, avant-garde fiction, etc. (Author/RB)

  4. Eye Wear: MedlinePlus Health Topic

    Science.gov (United States)

    ... When You Exercise (National Institute on Aging) - PDF Topic Image MedlinePlus Email Updates Get Eye Wear updates by email What's this? GO Related Health Topics Refractive Errors National Institutes of Health The primary ...

  5. The model of the dependence of the abrasive wear value on the maximal linear wear

    Directory of Open Access Journals (Sweden)

    О.А. Вишневський

    2004-01-01

    Full Text Available  The relation of the contact area of the rubber roll with a sample and the maximal linear wear value is found. The mathematical model of the dependence of the wear volume weight value on the maximal dimple depth is presented with the friction on abrasive particles fixed nonrigidly. The relation of volume weight wear with the rubber roll contact surface area with a sample with the friction on abrasive particles fixed nonrigidly is established.

  6. Biocompatible wear-resistant thick ceramic coating

    Directory of Open Access Journals (Sweden)

    Vogt Nicola

    2016-09-01

    Full Text Available Sensitisation to immunologically active elements like chromium, cobalt or nickel and debris particle due to wear are serious problems for patients with metallic implants. We tested the approach of using a hard and thick ceramic coating as a wear-resistant protection of titanium implants, avoiding those sensitisation and foreign body problems. We showed that the process parameters strongly influence the coating porosity and, as a consequence, also its hardness.

  7. Third abrasive wear mode: is it possible?

    Directory of Open Access Journals (Sweden)

    Ronaldo Câmara Cozza

    2014-04-01

    Full Text Available The objective of this paper is to propose an initial discussion on the characterization of a third abrasive wear mode. The results obtained in a previous work [1] under different test conditions revealed the occurrence of the superposition of the “rolling” and “grooving” abrasive wear modes. This phenomenon was denoted “micro-rolling abrasion” due to the observation that “rolling abrasion” was found to act on “grooving abrasion”.

  8. Assessing and Predicting Erosion from Off Highway Vehicle Trails in Front-Range Rocky Mountain Watersheds.

    Science.gov (United States)

    Howard, M. J.; Silins, U.; Anderson, A.

    2016-12-01

    Off highway vehicle (OHV) trails have the potential to deliver sediment to sensitive headwater streams and increased OHV use is a growing watershed management concern in many Rocky Mountain regions. Predictive tools for estimating erosion and sediment inputs are needed to support assessment and management of erosion from OHV trail networks. The objective of this study was to a) assess erodibility (K factor) and total erosion from OHV trail networks in Rocky Mountain watersheds in south-west Alberta, Canada, and to b) evaluate the applicability of the Universal Soil Loss Equation (USLE) for predicting OHV trail erosion to support erosion management strategies. Measured erosion rates and erodibility (K) from rainfall simulation plots on OHV trails during the summers of 2014 and 2015 were compared to USLE predicted erosion from these same trails. Measured erodibility (K) from 23 rainfall simulation plots was highly variable (0.001-0.273 Mg*ha*hr/ha*MJ*mm) as was total seasonal erosion from 52 large trail sections (0.0595-43.3 Mg/ha) across trail segments of variable slope, stoniness, and trail use intensity. In particular, intensity of trail use had a large effect on both erodibility and total erosion that is not presently captured by erodibility indices (K) derived from soil characteristics. Results of this study suggest that while application of USLE for predicting erosion from OHV trail networks may be useful for initial coarse erosion assessment, a better understanding of the effect of factors such as road/trail use intensity on erodibility is needed to support use of USLE or associated erosion prediction tools for road/trail erosion management.

  9. Auto consolidated cohesive sediments erosion

    International Nuclear Information System (INIS)

    Ternat, F.

    2007-02-01

    Pollutants and suspended matters of a river can accumulate into the sedimentary column. Once deposited, they are submitted to self-weight consolidation processes, ageing and burying, leading to an increase of their erosion resistance. Pollutant fluxes can be related to sedimentary fluxes, determined by threshold laws. In this work, an erosion threshold model is suggested by introducing a cohesion force into the usual force balance. A model of cohesion is developed on the basis of interactions between argillaceous cohesive particles (clays), particularly the Van der Waals force, whose parameterization is ensured by means of granulometry and porosity. Artificial erosion experiments were performed in a recirculating erosion flume with natural cored sediments where critical shear stress measurements were performed. Other analyses provided granulometry and porosity. The results obtained constitute a good database for the literature. The model is then applied to the experimental conditions and gives good agreement with measurements. An example of the accounting for self-weight consolidation processes is finally suggested, before finishing on a Mohr like diagram dedicated to soft cohesive sediment erosion. (author)

  10. Pseudomembranous candidiasis in patient wearing full denture

    Directory of Open Access Journals (Sweden)

    Nurdiana Nurdiana

    2009-06-01

    Full Text Available Background: Oral candidiasis is a common opportunistic infection of the oral cavity caused by an overgrowth of Candida species, the commonest being Candida albicans. Candida albicans is a harmless commensal organism inhabiting the mouths but it can change into pathogen and invade tissue and cause acute and chronic disease. Dentures predispose to infection with Candida in as many as 65% of elderly people wearing full upper dentures. Purpose: The purpose of this case report is to discuss thrush in patient wearing full denture which rapidly developed. Case: This paper report a case of 57 year-old man who came to the Oral Medicine Clinic Faculty of Dentistry Airlangga University with clinical appearance of pseudomembranous candidiasis (thrush. Case Management: Diagnosis of this case is confirmed with microbiology examination. Patient was wearing full upper dentures, and from anamnesis known that patient wearing denture for 24 hours and he had poor oral hygiene. Patient was treated with topical (nystatin oral suspension and miconazole oral gel and systemic (ketoconazole antifungal. Patient also instructed not to wear his denture and cleaned white pseudomembrane on his mouth with soft toothbrush. Conclusion: Denture, habit of wearing denture for 24 hours, and poor oral hygiene are predisposing factors of thrush and it can healed completely after treated with topical and systemic antifungal.

  11. Grain size dependence of wear in ceramics

    International Nuclear Information System (INIS)

    Wu, C.C.; Rice, R.W.; Johnson, D.; Platt, B.A.

    1985-01-01

    Pin-On-Disk (POD), microwear tests of Al 2 O 3 , MgO, MgAl 2 O 4 , and ZrO 2 , most being dense and essentially single phase, showed the reciprocal of wear following a hall-petch type relationship. However, extrapolation to infinite grain size always gave a lower intercept than most or all single-crystal values; in particular, Al 2 O 3 data projects to a negative intercept. Initial macro wear tests of some of the same Al 2 O 3 materials also indicate a hall-petch type grain-size dependence, but with a greatly reduced grain-size dependence, giving a positive hall-petch intercept. Further, the macrowear grain-size dependence appears to decrease with increased wear. It is argued that thermal expansion anisotropy (of Al 2 O 3 ) significantly affects the grain size dependence of POD wear, in particular, giving a negative intercept, while elastic anisotropy is suggested as a factor in the grain-size dependence of the cubic (MgO, MgAl 2 O 4 , and ZrO 2 ) materials. The reduced grain-size dependence in the macrowear tests is attributed to overlapping wear tracks reducing the effects of enhanced wear damage, e.g., from elastic and thermal expansion anisotropies

  12. Communicating and Visualizing Erosion-associated Risks to Infrastructure

    Science.gov (United States)

    Hewett, Caspar; Simpson, Carolyn; Wainwright, John

    2016-04-01

    Soil erosion is a major problem worldwide, affecting agriculture, the natural environment and urban areas through its impact on flood risk, water quality, loss of nutrient-rich upper soil layers, eutrophication of water bodies, sedimentation of waterways and sediment-related damage to roads, buildings and infrastructure such as water, gas and electricity supply networks. This study focuses on risks to infrastructure associated with erosion and the interventions needed to reduce those risks. Deciding on what interventions to make means understanding better which parts of the landscape are most susceptible to erosion and which measures are most effective in reducing it. Effective ways of communicating mitigation strategies to stakeholders such as farmers, land managers and policy-makers are then essential if interventions are to be implemented. Drawing on the Decision-Support Matrix (DSM) approach which combines a set of hydrological principles with Participatory Action Research (PAR), a decision-support tool for Communicating and Visualizing Erosion-Associated Risks to Infrastructure (CAVERTI) was developed. The participatory component was developed with the Wear Rivers Trust, focusing on a case-study area in the North East of England. The CAVERTI tool brings together process understanding gained from modelling with knowledge and experience of a variety of stakeholders to address directly the problem of sediment transport. Development of the tool was a collaborative venture, ensuring that the problems and solutions presented are easily recognised by practitioners and decision-makers. This recognition, and ease of access via a web-based interface, in turn help to ensure that the tools get used. The web-based tool developed helps to assess, manage and improve understanding of risk from a multi-stakeholder perspective and proposes solutions to problems. We argue that visualization and communication tools co-developed by researchers and stakeholders are the best means

  13. Wear Behavior of Woven Roving Aramid / Epoxy Composite under Different Conditions

    Directory of Open Access Journals (Sweden)

    Asad A. Khalid

    2012-09-01

    Full Text Available Wear behavior studies of aramid woven roving /epoxy composite has been conducted. Sliding the material against smooth steel counter face under dry and  lubricated with oil conditions has been investigated. Powder of Silicon carbide has been mixed with the epoxy resin and tested also. The powder was mixed in a volumetric fraction of 10% with the epoxy resin. Four Laminates of six layers were fabricated by hand lay up  method. A pin on disc apparatus has been fabricated to conduct the sliding wear tests on specimens of (4 mm   4 mm   12 mm in size have been cut from the four laminates. The effect of sliding condition including dry, lubricated, dry with additives and lubricated with additives have been studied. Wear rate tests have been conducted at different sliding speeds and loads. Results show that the wear characteristics are influenced by the operating conditions and the construction of the composite material used. It was also found that the wear of aramid /epoxy composite onto the steel counter face were significantly reduced by using lubricant and additives but still took place.Keywords: Wear, Composite materials, Woven roving aramid, Epoxy, Additives, Lubricant.

  14. Bentonite erosion. Laboratory studies

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Mats (Div. of Nuclear Chemistry, Royal Inst. of Technology, Stockholm (Sweden), School of Chemical Science and Engineering)

    2009-11-15

    This report covers the laboratory studies that have been performed at Nuclear Chemistry, KTH in the project 'Bentonite Erosion'. Many of the experiments in this report were performed to support the work of the modelling group and were often relatively simple. One of the experiment series was performed to see the impact of gravity and concentration of mono- and di-valent cations. A clay suspension was prepared in a test tube. A net was placed in contact with the suspension, the test tube was filled with solutions of different concentrations and the system was left overnight to settle. The tube was then turned upside down and the behaviour was visually observed. Either the clay suspension fell through the net or stayed on top. By using this method surprisingly sharp determinations of the Critical Coagulation (Flocculation) Concentration (CCC/CFC) could be made. The CCC/CFC of Ca2+ was for sodium montmorillonite determined to be between 1 and 2 mM. An artificial fracture was manufactured in order to simulate the real case scenario. The set-up was two Plexiglas slabs separated by 1 mm thick spacers with a bentonite container at one side of the fracture. Water was pumped with a very low flow rate perpendicular to bentonite container and the water exiting the fracture was sampled and analyzed for colloid content. The bentonite used was treated in different ways. In the first experiment a relatively montmorillonite rich clay was used while in the second bentonite where only the readily soluble minerals had been removed was used. Since Plexiglas was used it was possible to visually observe the bentonite dispersing into the fracture. After the compacted bentonite (1,000 kg/m3) had been water saturated the clay had expanded some 12 mm out into the fracture. As the experiment progressed the clay expanded more out into the fracture and seemed to fractionate in two different phases with less material in the outmost phase. A dark rim which was later analyzed to contain

  15. Bentonite erosion - Laboratory studies

    International Nuclear Information System (INIS)

    Jansson, Mats

    2010-01-01

    Document available in extended abstract form only. Bentonite clay is proposed as buffer material in the KBS-3 concept of storing spent nuclear fuel. Since the clay is plastic it will protect the canisters containing the spent fuel from movements in the rock. Furthermore, the clay will expand when taking up water, become very compact and hence limit the transport of solutes to and from the canister to only diffusion. The chemical stability of the bentonite barrier is of vital importance. If much material would be lost the barrier will lose its functions. As a side effect, lots of colloids will be released which may facilitate radionuclide transport in case of a breach in the canister. There are scenarios where during an ice age fresh melt water may penetrate down to repository depths with relatively high flow rates and not mix with older waters of high salinity. Under such conditions bentonite colloids will be more stable and there is a possibility that the bentonite buffer would start to disperse and bentonite colloids be carried away by the passing water. This work is a part of a larger project called Bentonite Erosion, initiated and supported by SKB. In this work several minor experiments have been performed in order to investigate the influence of for instance di-valent cations, gravity, etc. on the dispersion behaviour of bentonite and/or montmorillonite. A bigger experiment where the real situation was simulated using an artificial fracture was conducted. Two Plexiglas slabs were placed on top of each other, separated by plastic spacers. Bentonite was placed in a container in contact with a fracture. The bentonite was water saturated before deionized water was pumped through the fracture. The evolution of the bentonite profile in the fracture was followed visually. The eluate was collected in five different slots at the outlet side and analyzed for colloid concentration employing Photon Correlation Spectroscopy (PCS) and a Single Particle Counter (SPC). Some

  16. Effect of wear parameters on dry sliding behavior of Fly Ash/SiC particles reinforced AA 2024 hybrid composites

    Science.gov (United States)

    Bhaskar Kurapati, Vijaya; Kommineni, Ravindra

    2017-09-01

    In the present work AA 2024 alloy reinforced with mixtures of SiC and Fly Ash (FA) particles of 70 µm (5, 10 and 15 wt. %) are fabricated using the stir casting method. Both reinforcements are added in equal weight proportions. The wear test specimens are prepared from both the alloy and composite castings in the dimensions of Ф 4 mm and 30 mm lengths by the wire cut EDM process. The dry sliding wear properties of the prepared composites at room temperature are estimated by pin-on-disc wear testing equipment. The wear characteristics of the composites are studied by conducting the dry sliding wear test over loads of 0.5 Kgf, 1.0 Kgf, 1.5 Kgf, a track diameter of 60 mm and sliding times of 15 min, 30 min, 45min. The experimental results shows that the wear decreases with an increase in the weight percentage of FA and SiC particles in the matrix. Additionally wear increases with an increase in load and sliding time. Further, it is found that the wear resistance of the AA2024-Hybrid composites is higher than that of the AA2024 matrix.

  17. Spatial distribution models of erosion on slopes cultivated with vineyards

    International Nuclear Information System (INIS)

    Armaez, J.; Ortigosa, L.; Ruiz-Falno, P.; Llorente, J. A.; Lasanta, T.

    2009-01-01

    Soils cultivated with vineyards have high rates of erosion. In the Mediterranean area, this is related to the environmental characteristics and the management of cultivation techniques. Indeed, in this region the rainfall intensity and the location of vineyards on slopes favour the erosive activity of runoff. The total area of vineyards in La Rioja (Spain) is currently almost 40,000 ha. Vineyards are located on hillsides between 400 and 60 m.a.s.l. Of the vineyards of La Rioja 81,7% are planted on slopes with a gradient between 3 degree centigrade and 9 degree centigrade. (Author) 5 refs.

  18. Interfacial reaction effects on erosion of aluminum matrix composites

    International Nuclear Information System (INIS)

    Tu, J.P.; Hiroshima Univ., Higashi-Hiroshima; Matsumura, M.

    1999-01-01

    Alumina borate (A 18 B 4 O 33 ) whisker reinforced aluminum composites have attracted interest because of their high specific strength, high modulus and low cost. An obvious feature of the microstructure in A 18 B 4 O 33 /Al composite is that an interfacial reaction exists between the whisker and the aluminum alloy. In order to discuss the influence of interface interaction between the whisker and matrix on the erosion resistance of composites, two reaction treatments are conducted. From the results of the treated composites, it can be obtained about the erosion characteristics of the composite materials under steady-state conditions

  19. Carbon-Based Wear Coatings: Properties and Applications

    Science.gov (United States)

    Miyoshi, Kazuhisa

    2003-01-01

    and friction; thermal conductivity; chemical and thermal inertness; corrosion and wear resistance; radiation resistance and biocompatibility; electronic, acoustic, and electrochemical characteristics; and environmental compatibility. These properties make diamond attractive for a wide range of diverse applications. In particular, chemical-vapor-deposited (CVD) diamond coatings offer a broad potential, since size and cost are not as limiting. The production of large, superhard diamond films or sheets at low cost make designer materials possible. This presentation is divided into two sections: properties and applications of hard coatings. The first section is concerned with the fundamental properties of the surfaces of CVD diamonds and related materials. The surface properties of hard coatings with favorable coefficients of friction (less than or equal to 0.1) and dimensional wear coefficients (less than or equal to 10(exp -6) cubic millimeters/N.m) in specific environments are discussed. The second section is devoted to applications. Examples of actual, successful applications and of potential challenging applications of the coatings.such as CVD diamond, diamondlike carbon, and cubic boron nitride-are described. Cutting tools coated with CVD diamond are of immediate commercial interest. Other applications, such as microelectromechanical systems (MEMS), valves, and bearings of CVD diamond, are being developed, but at a slow pace. There is a continually growing interest in commercializing diamondlike carbon for wear parts applications, such as biomedical parts and implants, forming dies, transport guides, magnetic tapes and disks, valves, and gears. Cubic boron nitride films are receiving attention because they can be used on tools to machine ferrous materials or on wear parts in sliding contact with ferrous materials.

  20. Determining long-term regional erosion rates using impact craters

    Science.gov (United States)

    Hergarten, Stefan; Kenkmann, Thomas

    2015-04-01

    More than 300,000 impact craters have been found on Mars, while the surface of Moon's highlands is even saturated with craters. In contrast, only 184 impact craters have been confirmed on Earth so far with only 125 of them exposed at the surface. The spatial distribution of these impact craters is highly inhomogeneous. Beside the large variation in the age of the crust, consumption of craters by erosion and burial by sediments are the main actors being responsible for the quite small and inhomogeneous crater record. In this study we present a novel approach to infer long-term average erosion rates at regional scales from the terrestrial crater inventory. The basic idea behind this approach is a dynamic equilibrium between the production of new craters and their consumption by erosion. It is assumed that each crater remains detectable until the total erosion after the impact exceeds a characteristic depth depending on the crater's diameter. Combining this model with the terrestrial crater production rate, i.e., the number of craters per unit area and time as a function of their diameter, allows for a prediction of the expected number of craters in a given region as a function of the erosion rate. Using the real crater inventory, this relationship can be inverted to determine the regional long-term erosion rate and its statistical uncertainty. A limitation by the finite age of the crust can also be taken into account. Applying the method to the Colorado Plateau and the Deccan Traps, both being regions with a distinct geological history, yields erosion rates in excellent agreement with those obtained by other, more laborious methods. However, these rates are formally exposed to large statistical uncertainties due to the small number of impact craters. As higher crater densities are related to lower erosion rates, smaller statistical errors can be expected when large regions in old parts of the crust are considered. Very low long-term erosion rates of less than 4

  1. Soil erosion in Slovene Istria

    Directory of Open Access Journals (Sweden)

    Matjaž Mikoš

    2009-12-01

    Full Text Available From the end of nineties of the 20th century, intense hydrologic and geomorphologic research is taking place in the Slovene Istria. As a part of this research also studies on soil erosion were undertaken in the period from 2005 to 2008. The field measurements were under taken onclosed 1m2 large erosion plots under three different land uses (on bare soils in an olive grove, on an overgrown meadow, in a forest, placed south of the Marezige village in the Rokava River basin.We show weekly measurements of surface erosion (interrill erosion for the period of 13 months (the end of March 2005 – the end of April 2006, as well as monthly and seasonal averages together with selected linear statistical correlations between soil erosion and weather parameters.From May 2005 to April 2006 the interrill erosion on bare soils in an olive grove with an inclination of 5.5° amounted to 9013 g/m2 (90 t/ha that corresponds to surface lowering rate of 8.5 mm/yr; on an overgrown meadow with an inclination of 9.4° it amounted to 168 g/m2 (1,68 t/ha that corresponds to surface lowering rate of 0.16 mm//yr; and in a forest with an inclination of 7.8° it amounted to 391 g/m2 (3,91 t/ha and in a forest with an inclination of 21.4° it amounted to 415 g/m2 (4,15 t/ha, respectively, that corresponds to surface lowering rate of 0.4 mm/yr.

  2. Wear-resistance of Aluminum Matrix Microcomposite Materials

    Directory of Open Access Journals (Sweden)

    M. Kandeva

    2011-03-01

    Full Text Available A procedure is developed for the study of wear of aluminum alloys AlSi7 obtained by casting, reinforced by TiC microparticles, before and after heat treatment. Tribological study is realized under conditions of friction on counterbody with fixed abrasive. Experimental results were obtained for mass wear, wear rate, wear intensity and wear-resistance of the alloys with different wt% of microparticles.

  3. Características da chuva e perdas por erosão sob diferentes práticas de manejo do solo Rainfall characteristics and erosion losses for different soil management practices

    Directory of Open Access Journals (Sweden)

    Daniel F. de Carvalho

    2009-02-01

    Full Text Available Objetivou-se com este trabalho, avaliar as relações entre a erosividade da chuva e os padrões da precipitação com as perdas por erosão, para diferentes tipos de preparo do solo em um Argissolo Vermelho-Amarelo. O experimento foi conduzido utilizando-se parcelas experimentais de perda de solo com dimensões de 3,5 x 22,0 m, com os seguintes tratamentos: preparo convencional do solo em nível e semeadura de Mucuna Cinza (Mucuna pruriens, Crotalária (Crotalaria juncea, e Milho (Zea mays L.; preparo convencional do solo no sentido do declive e semeadura de milho no mesmo sentido e preparo convencional do solo no sentido do declive, mantido sem qualquer tipo de cobertura. Foi possível evidenciar que as perdas de solo foram mais influenciadas pelos diferentes tratamentos que as perdas de água; os tratamentos Crotalária e Milho morro abaixo, foram aqueles que apresentaram, respectivamente, as menores e maiores perdas de solo e água e, em média, os eventos de precipitação caracterizados como avançado, intermediário e atrasado, foram responsáveis por 62,6, 11,8 e 25,6% das perdas de água e por 35,1, 6,6 e 58,3% das perdas de solo, respectivamente.This study was carried out in order to evaluate the relation between erosivity index and the rainfall pattern associated with different kinds of soil preparation and cover with erosion losses in a Red Yellow Argisol. The experiment was conducted in five soil loss experimental plots of 3.5 x 22.0 m, with the following treatments: conventional tillage (plowing plus disking in contour lines and sowing the velvet bean (Mucuna pruriens, sun hemp (Crotalaria juncea and corn (Zea mays L.; conventional tillage (plowing plus disking in slope line and sowing of corn, conventional tillage (plowing plus disking in slope line and without soil cover. The results showed that soil loss was more affected by different treatments than water loss; the treatments sun hemp and corn sowed in slope line were those

  4. Creating a Bio-Inspired Solution to Prevent Erosion

    Science.gov (United States)

    Reher, R.; Martinez, A.; Cola, J.; Frost, D.

    2016-12-01

    Through the study of geophysical sciences, lessons can be developed which allow for the introduction of bio-inspired design and art concepts to K-5 elementary students. Students are placed into an engineering mindset in which they must apply the concepts of bio-geotechnics to observe how we can use nature to prevent and abate erosion. Problems are staged for students using realistic engineering scenarios such as erosion prevention through biomimicry and the study of anchorage characteristics of root structures in regard to stability of soil. Specifically, a lesson is introduced where students research, learn, and present information about bio-inspired designs to understand these concepts. They lean how plant roots differ in size and shape to stabilize soil. In addition, students perform a series of hands-on experiments which demonstrate how bio-cements and roots can slow erosion.

  5. Geotribology - Friction, wear, and lubrication of faults

    Science.gov (United States)

    Boneh, Yuval; Reches, Ze'ev

    2018-05-01

    We introduce here the concept of Geotribology as an approach to study friction, wear, and lubrication of geological systems. Methods of geotribology are applied here to characterize the friction and wear associated with slip along experimental faults composed of brittle rocks. The wear in these faults is dominated by brittle fracturing, plucking, scratching and fragmentation at asperities of all scales, including 'effective asperities' that develop and evolve during the slip. We derived a theoretical model for the rate of wear based on the observation that the dynamic strength of brittle materials is proportional to the product of load stress and loading period. In a slipping fault, the loading period of an asperity is inversely proportional to the slip velocity, and our derivations indicate that the wear-rate is proportional to the ratio of [shear-stress/slip-velocity]. By incorporating the rock hardness data into the model, we demonstrate that a single, universal function fits wear data of hundreds of experiments with granitic, carbonate and sandstone faults. In the next step, we demonstrate that the dynamic frictional strength of experimental faults is well explained in terms of the tribological parameter PV factor (= normal-stress · slip-velocity). This factor successfully delineates weakening and strengthening regimes of carbonate and granitic faults. Finally, our analysis revealed a puzzling observation that wear-rate and frictional strength have strikingly different dependencies on the loading conditions of normal-stress and slip-velocity; we discuss sources for this difference. We found that utilization of tribological tools in fault slip analyses leads to effective and insightful results.

  6. Contact damage failure analyses of fretting wear behavior of the metal stem titanium alloy-bone cement interface.

    Science.gov (United States)

    Zhang, Lanfeng; Ge, Shirong; Liu, Hongtao; Wang, Qingliang; Wang, Liping; Xian, Cory J

    2015-11-01

    Although cemented titanium alloy is not favored currently in the Western world for its poor clinical and radiography outcomes, its lower modulus of elasticity and good biocompatibility are instrumental for its ability supporting and transforming physical load, and it is more suitable for usage in Chinese and Japanese populations due to their lower body weights and unique femoral characteristics. Through various friction tests of different cycles, loads and conditions and by examining fretting hysteresis loops, fatigue process curves and wear surfaces, the current study investigated fretting wear characteristics and wear mechanism of titanium alloy stem-bone cement interface. It was found that the combination of loads and displacement affected the wear quantity. Friction coefficient, which was in an inverse relationship to load under the same amplitude, was proportional to amplitudes under the same load. Additionally, calf serum was found to both lubricate and erode the wear interface. Moreover, cement fatigue contact areas appeared black/oxidative in dry and gruel in 25% calf serum. Fatigue scratches were detected within contact areas, and wear scars were found on cement and titanium surfaces, which were concave-shaped and ring concave/ convex-shaped, respectively. The coupling of thermoplastic effect and minimal torque damage has been proposed to be the major reason of contact damage. These data will be important for further studies analyzing metal-cement interface failure performance and solving interface friction and wear debris production issues. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Abrasive wear of ceramic wear protection at ambient and high temperatures

    Science.gov (United States)

    Varga, M.; Adam, K.; Tumma, M.; Alessio, K. O.

    2017-05-01

    Ceramic wear protection is often applied in abrasive conditions due to their excellent wear resistance. This is especially necessary in heavy industries conveying large amounts of raw materials, e.g. in steel industry. Some plants also require material transport at high temperatures and velocities, making the need of temperature stable and abrasion resistant wear protection necessary. Various types and wear behaviour of ceramic protection are known. Hence, the goal of this study is to identify the best suitable ceramic materials for abrasive conditions in harsh environments at temperatures up to 950°C and severe thermal gradients. Chamottes, known for their excellent thermal shock resistance are compared to high abrasion resistant ceramic wear tiles and a cost efficient cement-bounded hard compound. Testing was done under high-stress three-body abrasion regime with a modified ASTM G65 apparatus enabling for investigations up to ~950°C. Thereto heated abrasive is introduced into the wear track and also preheated ceramic samples were used and compared to ambient temperature experiments. Results indicate a significant temperature influence on chamottes and the hard compound. While the chamottes benefit from temperature increase, the cement-bounded hard compound showed its limitation at abrasive temperatures of 950°C. The high abrasion resistant wear tiles represented the materials with the best wear resistance and less temperature influence in the investigated range.

  8. Quantitive dynamical wear analysis and the convergent quest for significant wear reduction

    International Nuclear Information System (INIS)

    Sellschop, F.; Kirsch, J.; Derry, T.; Marcus, R.

    1984-01-01

    The maturing of nuclear physics has made the development of ion beam modification of materials possible, bringing new skills and prospects to the world of materials science. In the following paper an outline is given of the history of ion beam modification of materials (IBMM) and its use for altering the surface of metals to combat wear and friction, and monitoring wear in engines

  9. Wear mechanisms and friction parameters for sliding wear of micron-scale polysilicon sidewalls

    NARCIS (Netherlands)

    Alsem, D. H.; van der Hulst, R.; Stach, E. A.; Dugger, M. T.; De Hosson, J. Th. M.; Ritchie, R. O.

    As tribological properties are critical factors in the reliability of silicon-based microelectromechanical systems, it is important to understand what governs wear and friction. Average dynamic friction, wear volumes and morphology have been studied for polysilicon devices fabricated using the

  10. Integrated spatial assessment of wind erosion risk in Hungary

    Directory of Open Access Journals (Sweden)

    L. Pásztor

    2016-11-01

    Full Text Available Wind erosion susceptibility of Hungarian soils was mapped on the national level integrating three factors of the complex phenomenon of deflation (physical soil features, wind characteristics, and land use and land cover. Results of wind tunnel experiments on erodibility of representative soil samples were used for the parametrization of a countrywide map of soil texture compiled for the upper 5 cm layer of soil, which resulted in a map representing threshold wind velocity exceedance. Average wind velocity was spatially estimated with 0.5′ resolution using the Meteorological Interpolation based on Surface Homogenised Data Basis (MISH method elaborated for the spatial interpolation of surface meteorological elements. The probability of threshold wind velocity exceedance was determined based on values predicted by the soil texture map at the grid locations. Ratio values were further interpolated to a finer 1 ha resolution using sand and silt content of the uppermost (0–5 cm layer of soil as spatial co-variables. Land cover was also taken into account, excluding areas that are not relevant to wind erosion (forests, water bodies, settlements, etc., to spatially assess the risk of wind erosion. According to the resulting map of wind erosion susceptibility, about 10 % of the total area of Hungary can be identified as susceptible to wind erosion. The map gives more detailed insight into the spatial distribution of wind-affected areas in Hungary compared to previous studies.

  11. Assessment of soil erosion sensitivity and post-timber-harvesting erosion response in a mountain environment of Central Italy

    Science.gov (United States)

    Borrelli, Pasquale; Schütt, Brigitta

    2014-01-01

    This study aimed to assess the effects of forest management on the occurrence of accelerated soil erosion by water. The study site is located in a mountainous area of the Italian Central Apennines. Here, forest harvesting is a widespread forestry activity and is mainly performed on the moderate to steep slopes of the highlands. Through modeling operations based on data on soil properties and direct monitoring of changes in the post-forest-harvesting soil surface level at the hillslope scale, we show that the observed site became prone to soil erosion after human intervention. Indeed, the measured mean soil erosion rate of 49 t ha- 1 yr- 1 for the harvested watershed is about 21 times higher than the rate measured in its neighboring undisturbed forested watershed (2.3 t ha- 1 yr- 1). The erosive response is greatly aggravated by exposing the just-harvested forest, with very limited herbaceous plant cover, to the aggressive attack of the heaviest annual rainfall without adopting any conservation practices. The erosivity of the storms during the first four months of field measurements was 1571 MJ mm h- 1 ha- 1 in total (i.e., from September to December 2008). At the end of the experiment (16 months), 18.8%, 26.1% and 55.1% of the erosion monitoring sites in the harvested watershed recorded variations equal or greater than 0-5, 5-10 and > 10 mm, respectively. This study also provides a quantification of Italian forestland surfaces with the same pedo-lithological characteristics exploited for wood supply. Within a period of ten years (2002-2011), about 9891 ha of coppice forest changes were identified and their potential soil erosion rates modeled.

  12. Dental erosion caused by gastroesophageal reflux disease: a case report.

    Science.gov (United States)

    Cengiz, Seda; Cengiz, M Inanç; Saraç, Y Sinasi

    2009-07-22

    Chronic regurgitation of gastric acids in patients with gastroesophageal reflux disease may cause dental erosion, which can lead in combination with attrition or bruxism to extensive loss of coronal tooth tissue. This clinical report describes treatment of severe tooth wear of a gastroesophageal reflux disease patient who is 54-year-old Turkish male patient. After his medical treatment, severe tooth wear, bruxism and decreased vertical dimensions were determined. The vertical dimension was re-established and maxillary and mandibular anterior and posterior teeth were prepared for metal-ceramic restorations. Metal-ceramic fixed partial dentures were fabricated as full mouth restorations for both maxillary and mandibular arches because of splinting all teeth. And then maxillary stabilization splint was fabricated for his bruxism history. Significant loss of coronal tooth structure must taken into consideration. Gastroesophageal reflux disease by itself or in combination with attrition, abrasion or bruxism may be responsible for the loss. An extensive diagnostic evaluation is essential for the medical and dental effects of the problem.

  13. Effect of Microstructure on the Wear Behavior of Heat Treated SS-304 Stainless Steel

    Directory of Open Access Journals (Sweden)

    S. Kumar

    2016-12-01

    Full Text Available Sliding wear characteristics of some heat treated SS-304 stainless steel against EN-8 steel in dry condition have been studied in the present experimental work. Samples of SS-304 stainless steel have been heated in a muffle furnace in desired temperature and allowed to dwell for two hours. The heated specimen are then cooled in different media namely inside the furnace, open air, cutting grade oil (grade 44 and water at room temperature to obtain different grades of heat treatment. Microstructures and corresponding micro hardness of the samples have been measured along with Feritscopic studies. Wear characteristics have been studied in a multi tribo-tester (Ducom in dry sliding condition against EN-8 steel roller. Speed, load on job and duration of test run have been considered as the experimental parameters. The wear of the samples have been obtained directly from ‘Winducom 2006’ software. Mass loss of the samples before and after operation has also been considered as the measure of wear in the present study. All the samples have been slid against EN-8 steel roller with fixed experimental parameters. The data have been plotted, compared and analyzed. Effect of microstructures as well as micro hardness on the wear behavior has been studied and concluded accordingly.

  14. Analysis of mechanism of carbide tool wear and control by wear process

    Directory of Open Access Journals (Sweden)

    Pham Hoang Trung

    2017-01-01

    Full Text Available The analysis of physic-mechanical and thermal physic properties of hard alloys depending on their chemical composition is conducted. The correlation of cutting properties and regularities of carbide tool wear with cutting conditions and thermal physic properties of tool material are disclosed. Significant influence on the tool wear of not only mechanical, but, in the first place, thermal physic properties of tool and structural materials is established by the researches of Russian scientists, because in the range of industrial used cutting speeds the cause of tool wear are diffusion processes. The directions of intensity decreasing of tool wear by determining rational processing conditions, the choice of tool materials and wear-resistant coating on tool surface are defined.

  15. The effect of magnesium hydroxide-containing dentifrice using an extrinsic and intrinsic erosion cycling model.

    Science.gov (United States)

    Passos, Vanara Florêncio; Rodrigues, Lidiany Karla Azevedo; Santiago, Sérgio Lima

    2018-02-01

    To evaluate, in vitro, the effect of Mg(OH) 2 dentifrice, and the influence of the number of experimental days, on the extrinsic (citric acid -CA) and intrinsic (hydrochloric acid -HCl) enamel erosion models. Human enamel slabs were selected according to surface hardness and randomly assigned to 3 groups (n=9) as follows: non-fluoridated (negative control), NaF (1450ppm F- positive control) and Mg(OH) 2 (2%) dentifrices. The slabs were daily submitted to a 2-h period of pellicle formation and, over a period of 5days, submitted to cycles (3×/day) of erosive challenge (CA 0.05M, pH=3.75 or HCl 0.01M, pH=2 for 30s), treatment (1min -1:3w/w of dentifrice/distilled water) and remineralization (artificial saliva/120min). Enamel changes were determined by surface hardness loss (SHL) for each day and mechanical profilometry analysis. Data were analyzed by two-way ANOVA followed by Tukey's test to % SHL and one-way ANOVA to profilometry (pextrinsic acid erosion as determined by % SHL (pintrinsic model (p=0.295). With regards to surface wear, no statistically significant differences were found among the groups for CA (p=0.225) and HCl (p=0.526). The findings suggest that Mg(OH) 2 dentifrices might protect enamel against slight erosion, but protection was not effective for stronger acid erosion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. The prevalence of dental erosion in Nigerian patients with gastro-oesophageal reflux disease

    Directory of Open Access Journals (Sweden)

    Agbakwuru Elugwaraonu A

    2005-03-01

    Full Text Available Abstract Background In various people of the Western world, gastro-oesophageal reflux (GOR has been reported to be a common problem. Various studies have also assessed the relationship between GOR and dental erosion. The authors are not aware of such studies in Nigerians. It is therefore the aims of the present study to estimate the prevalence of GOR; to estimate the prevalence of dental erosion in patients with GORD; to document the oral findings in patients diagnosed with GORD and to compare these findings with previous studies elsewhere. Methods A total of 225 subjects comprising of 100 volunteers and 125 patients diagnosed with GORD were involved in this study. History of gastric juice regurgitation and heartburn were recorded. Oral examination to quantify loss of tooth structure was done using the tooth wear index (TWI designed by Smith and Knight (1984. Results Twenty patients with GORD presented with dental erosion in the maxillary anterior teeth with TWI scores ranging from 1–3. The prevalence of erosion was found to be statistically significant between GORD patients (16% and control (5% (p 0.05. Conclusion The present study supports the consideration of dental erosion as the extra-oesophageal manifestation of GORD. However the association between GORD and burning mouth sensation needs more investigation.

  17. Gastroesophageal reflux, dental erosion, and halitosis in epidemiological surveys: a systematic review.

    Science.gov (United States)

    Marsicano, Juliane A; de Moura-Grec, Patrícia G; Bonato, Rafaela C S; Sales-Peres, Matheus de Carvalho; Sales-Peres, Arsenio; Sales-Peres, Sílvia Helena de Carvalho

    2013-02-01

    In published studies, it has been suggested that dental wear is associated with gastroesophageal reflux disease (GERD). This systematic review was carried out to evaluate the association of GERD, dental erosion, and halitosis and to compare the indices adopted in epidemiological surveys. The Medline database (until October, 2011) was searched systematically to identify studies evaluating the prevalence of oral alterations, such as dental erosion and halitosis, in patients with GERD symptoms. Two reviewers analyzed all reports and the selected studies were evaluated according to the quality of evidence, using the validated Newcastle-Ottawa Quality Assessment Scale. Full-text copies of a total of 32 publications were obtained in duplicate. Sixteen publications were identified among the citations in the Bibliographic lists of studies that fulfilled the exclusion/inclusion criteria and quality of evidence. The relationship between dental erosion and GERD patients was significant in only seven studies. According to three studies, halitosis could be one of several extraesophageal symptoms or manifestations in GERD patients. In one study, it was found that the mucosa of GERD patients was significantly more acidic in comparison with that of the control group. This systematic review showed that there is a relationship between GERD and oral diseases (dental erosion and halitosis). The epidemiological surveys used different indices to analyze GERD and dental erosion. Further research could investigate the best method for assessing the two diseases.

  18. Dental Erosion and Dentin Hypersensitivity among Adult Asthmatics and Non-asthmatics Hospital-based: A Preliminary Study.

    Science.gov (United States)

    Farag, Zahra Hassan Abdelaziz; Awooda, Elhadi Mohieldin

    2016-01-01

    Asthma is a chronic inflammatory condition affecting the airways leading to spasm and swelling of the airways. The medications taken for the treatment of asthma can result in dental erosion and dentin hypersensitivity. The aims of this study were to investigate the severity of dental erosion amongst adult asthmatics according to: gender, type and duration of medication taken and to compare dental erosion and dentin hypersensitivity between asthmatics and non-asthmatics. Comparative, cross-sectional hospital based study among 40 asthmatics (M=15 & F=25) and 40 non-asthmatics (M=18 & F=22) in the age range of 18-60 year selected purposefully from Al-Shaab Teaching Hospital in Khartoum city. The Basic Erosive Wear Index was used for dental erosion assessment. Dentine hypersensitivity was determined by giving ice cold water and rated using the Visual Analogue Scale. Chi-square and Student's t-test were used for statistical analysis with P value ≤.05. There was an association between severity of dental erosion and presence of asthma (P=0.03), where asthmatics had a higher degree of erosion (moderate and severe) and non-asthmatics a lower degree. No significant association was found between dental erosion and gender, type and duration of medication among asthmatics group. A statistically significant difference was revealed in the degree of dentin hypersensitivity (P=0.00) among asthmatics (35.13%) and non-asthmatics (14.13%). Asthmatic patients had a higher degree of dental erosion and dentin hypersensitivity compared to non-asthmatics. Among asthmatic patients there was no association between severity of dental erosion and gender, type and duration medication was taken for.

  19. ELECTRIC FACTORS INFLUENCING THE COMPLEX EROSION PROCESSING BY INTRODUCING THE ELECTROLYTE THROUGH THE TRANSFER OBJECT

    Directory of Open Access Journals (Sweden)

    Alin Nioata

    2014-05-01

    Full Text Available The electric and electrochemical complex erosion processing is influenced by a great number of factors acting in tight interdependence and mutually influencing one another for achieving the stability of the processing process and achieving the final technological characteristics.The values taking part in developing the fundamental phenomena of the mechanism of complex erosion prevailing and contributes to the definition of technological characteristics, are factors.The paper presents the U potential difference and electric strength I as determining factors of the complex erosion process as well as other factors deriving from them: the current density, the power of the supply source.

  20. Dental erosion, prevalence and risk factors among a group of adolescents in Stockholm County.

    Science.gov (United States)

    Skalsky Jarkander, M; Grindefjord, M; Carlstedt, K

    2018-02-01

    To investigate the prevalence and risk factors of dental erosion (DE) among a group of adolescents in Stockholm County. This cross sectional cohort study was conducted at three clinics of the Public Dental Service in Stockholm County. Fifteen and 17 year old adolescents (1335) who scheduled their regular dental health examination were asked to participate. After drop-outs a sample of 1071 individuals, 547 males and 524 females were enrolled in the study. Presence of erosive wear was diagnosed (yes/no) on marker teeth by trained dentists/dental hygienists and photographs were taken. The adolescents answered a questionnaire regarding oral symptoms, dietary and behavioural factors. Two calibrated specialist dentists performed evaluation of the photographs for severity of DE using a modified version of the Simplified Erosion Partial Recording System (SEPRS). DE was clinically diagnosed in 28.3% of 15 years old and 34.3% of 17 years old. Severe erosive wear (grade 3 and 4 according to SEPRS) was found in 18.3% of the adolescents based upon the intra-oral photographs. DE was more prevalent and severe among males than females. Clinically diagnosed erosive lesions correlated significantly with soft drink consumption (p < 0.001), the use of juice or sport drinks as a thirst quencher after exercise (p = 0.006) and tooth hypersensitivity when eating and drinking (p = 0.012). Furthermore, self-assessed gastric reflux was a factor strongly associated with DE (p < 0.001). The study indicated that DE was common among adolescents in Stockholm County and associated with both internal and external risk factors.